{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","title_trans":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","temp":"true_false","correct":[["t","t","f","f"]],"list":[{"point":5,"col_name":["","\u0110\u00fang","Sai"],"arr_ques":["Trong hai cung tr\u00ean m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n, cung n\u00e0o c\u00f3 s\u1ed1 \u0111o nh\u1ecf h\u01a1n th\u00ec nh\u1ecf h\u01a1n","S\u1ed1 \u0111o c\u1ee7a n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n b\u1eb1ng ${{180}^{o}}$","V\u1edbi ba \u0111i\u1ec3m $A, B, C$ tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n ta lu\u00f4n c\u00f3: $\\text{s\u0111}\\overset\\frown{AB}=\\text{s\u0111}\\overset\\frown{AC}+\\text{s\u0111}\\overset\\frown{CB}$"],"explain":["\u0110\u00fang ","\u0110\u00fang (\u0110\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung)","Sai, v\u00ec kh\u1eb3ng \u0111\u1ecbnh tr\u00ean \u0111\u00fang n\u1ebfu $C$ l\u00e0 \u0111i\u1ec3m n\u1eb1m tr\u00ean cung $AB$ "]}]}],"id_ques":1621},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"Cho h\u00ecnh v\u1ebd: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D2.png' \/><\/center> <br\/> S\u1ed1 c\u1eb7p g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t cung l\u00e0:","select":["A. $2$ c\u1eb7p ","B. $3$ c\u1eb7p ","C. $4$ c\u1eb7p ","D. V\u00f4 s\u1ed1 c\u1eb7p "],"explain":" <span class='basic_left'> Ta c\u00f3: $\\widehat{BAC};\\,\\widehat{BDC}$ c\u00f9ng ch\u1eafn $\\overset\\frown{BC}$ <br\/> $\\widehat{ACB};\\,\\widehat{ADB}$ c\u00f9ng ch\u1eafn $\\overset\\frown{AB}$ <br\/> $\\widehat{DBC};\\,\\widehat{DAC}$ c\u00f9ng ch\u1eafn $\\overset\\frown{DC}$ <br\/> $\\widehat{ACD};\\,\\widehat{ABD}$ c\u00f9ng ch\u1eafn $\\overset\\frown{AD}$ <br\/> Suy ra c\u00f3 $4$ c\u1eb7p g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t cung <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C <\/span><\/span>","column":4}]}],"id_ques":1622},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["120"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"Cho tam gi\u00e1c \u0111\u1ec1u $ABC$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O)$. S\u1ed1 \u0111o cung nh\u1ecf $AC$ l\u00e0_input_ $^o$.","explain":" Ta c\u00f3: $\\widehat{ABC}={{60}^{o}}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c \u0111\u1ec1u) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AC}=2\\widehat{ABC}={{2.60}^{o}}={{120}^{o}}$ (\u0111\u1ecbnh l\u00ed g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $120$ <\/span><\/span> "}]}],"id_ques":1623},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["100"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D4.png' \/><\/center> <br\/> Bi\u1ebft $\\widehat{MDA}={{20}^{o}};\\,\\widehat{DMB}={{30}^{o}}.$ S\u1ed1 \u0111o $\\overset\\frown{DnB}$ l\u00e0 _input_ $^o$","explain":" <span class='basic_left'> Ta c\u00f3: $\\widehat{DAB}=\\widehat{ADM}+\\widehat{AMD}$ (\u0111\u1ecbnh l\u00ed g\u00f3c ngo\u00e0i t\u1ea1i m\u1ed9t \u0111\u1ec9nh c\u1ee7a $\\Delta MAD$) <br\/> $\\Rightarrow \\widehat{DAB}={{30}^{o}}+{{20}^{o}}={{50}^{o}}$ <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{DnB}=2\\widehat{DAB}={{2.50}^{o}}={{100}^{o}}$ (\u0111\u1ecbnh l\u00ed g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $100$ <\/span><\/span> "}]}],"id_ques":1624},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["40"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n $(O)$ \u0111\u01b0\u1eddng k\u00ednh $BC$ l\u1ea5y \u0111i\u1ec3m $A$ sao cho $\\widehat{ABC}={{70}^{o}}.$ C\u00e1c ti\u1ebfp tuy\u1ebfn t\u1ea1i $A$ v\u00e0 $C$ v\u1edbi \u0111\u01b0\u1eddng tr\u00f2n c\u1eaft nhau t\u1ea1i $M$. S\u1ed1 \u0111o $\\widehat{AMC}$ l\u00e0 _input_ $^o$","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D5.png' \/><\/center> Ta c\u00f3: $\\text{s\u0111}\\overset\\frown{AC}=2\\widehat{ABC}$ (\u0111\u1ecbnh l\u00ed g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AC}=2.70^o={{140}^{o}}$ <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{ABC}={{360}^{o}}-\\text{s\u0111}\\overset\\frown{AC}={{360}^{o}}-{{140}^{o}}={{220}^{o}}$ <br\/> L\u1ea1i c\u00f3: $\\widehat{AMC}=\\dfrac{\\text{s\u0111}\\overset\\frown{ABC}-\\text{s\u0111}\\overset\\frown{AC}}{2}$ (\u0111\u1ecbnh l\u00ed g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n) <br\/> $\\Rightarrow \\widehat{AMC}=\\dfrac{{{220}^{o}}-{{140}^{o}}}{2}={{40}^{o}}$<br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $40$ <\/span><\/span> "}]}],"id_ques":1625},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho \u0111\u01b0\u1eddng tr\u00f2n $(O)$ \u0111\u01b0\u1eddng k\u00ednh $AB=5cm$. Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n l\u1ea5y \u0111i\u1ec3m $C$ sao cho $\\widehat{BOC}={{60}^{o}}$. \u0110\u1ed9 d\u00e0i c\u1ea1nh $AC$ l\u00e0: ","select":["A. $\\dfrac{5\\sqrt{2}}{2}\\, cm$ ","B. $\\dfrac{5\\sqrt{3}}{2}\\, cm$","C. $\\dfrac{5}{2}\\, cm$","D. $\\dfrac{5\\sqrt{3}}{3}\\, cm$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D6.png' \/><\/center> <br\/> N\u1ed1i $O$ v\u1edbi $C$ <br\/> Ta c\u00f3: $\\widehat{ACB}=90^o$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) <br\/> $\\text{s\u0111}\\overset\\frown{BC}=\\widehat{BOC}={{60}^{o}}$ (\u0111\u1ecbnh l\u00ed g\u00f3c \u1edf t\u00e2m) <br\/> $\\Rightarrow \\widehat{CAB}=\\dfrac{1}{2}\\text{s\u0111}\\overset\\frown{BC}=\\dfrac{1}{2}{{.60}^{o}}={{30}^{o}}$ (\u0111\u1ecbnh l\u00ed g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> X\u00e9t $\\Delta ABC$ vu\u00f4ng t\u1ea1i $C$ c\u00f3: <br\/> $AC=AB.cos\\widehat{CAB}$ (t\u1ec9 s\u1ed1 l\u01b0\u1ee3ng gi\u00e1c c\u1ee7a g\u00f3c nh\u1ecdn) <br\/> $\\Rightarrow AC=5.cos{{30}^{o}}=\\dfrac{5\\sqrt{3}}{2}\\,(cm)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B <\/span><\/span>","column":4}]}],"id_ques":1626},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","title_trans":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","temp":"true_false","correct":[["t","f","t","f"]],"list":[{"point":5,"col_name":["","\u0110\u00fang","Sai"],"arr_ques":["Trong m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n, c\u00e1c g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t d\u00e2y th\u00ec b\u1eb1ng nhau","Trong m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n, n\u1ebfu cung nh\u1ecf c\u00f3 s\u1ed1 \u0111o l\u00e0 $\\alpha $ th\u00ec s\u1ed1 \u0111o cung l\u1edbn l\u00e0 ${{180}^{o}}-\\alpha $","G\u00f3c n\u1ed9i ti\u1ebfp l\u00e0 g\u00f3c vu\u00f4ng th\u00ec ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n","G\u00f3c t\u1ea1o b\u1edfi tia ti\u1ebfp tuy\u1ebfn v\u00e0 d\u00e2y cung l\u00e0 g\u00f3c c\u00f3 \u0111\u1ec9nh t\u1ea1i ti\u1ebfp \u0111i\u1ec3m v\u00e0 hai c\u1ea1nh l\u00e0 hai d\u00e2y cung."],"explain":["\u0110\u00fang, v\u00ec d\u00e2y c\u0103ng cung do \u0111\u00f3 c\u00e1c g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t d\u00e2y c\u0169ng c\u00f9ng ch\u1eafn m\u1ed9t cung","Sai, v\u00ec s\u1ed1 \u0111o cung c\u1ea3 \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 ${{360}^{o}}$ n\u00ean n\u1ebfu cung nh\u1ecf c\u00f3 s\u1ed1 \u0111o l\u00e0 $\\alpha $ th\u00ec s\u1ed1 \u0111o cung l\u1edbn l\u00e0 ${{360}^{o}}-\\alpha $","\u0110\u00fang, v\u00ec g\u00f3c n\u1ed9i ti\u1ebfp c\u00f3 s\u1ed1 \u0111o b\u1eb1ng m\u1ed9t n\u1eeda cung b\u1ecb ch\u1eafn (\u0111\u1ecbnh l\u00ed g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> N\u00ean g\u00f3c vu\u00f4ng ch\u1eafn cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng ${{180}^{o}}$ l\u00e0 n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n.","Sai v\u00ec g\u00f3c t\u1ea1o b\u1edfi tia ti\u1ebfp tuy\u1ebfn v\u00e0 d\u00e2y cung l\u00e0 g\u00f3c c\u00f3 \u0111\u1ec9nh t\u1ea1i ti\u1ebfp \u0111i\u1ec3m, m\u1ed9t c\u1ea1nh l\u00e0 tia ti\u1ebfp tuy\u1ebfn v\u00e0 c\u1ea1nh kia ch\u1ee9a d\u00e2y cung"]}]}],"id_ques":1627},{"time":24,"part":[{"time":3,"title":"N\u1ed1i t\u1eeb ho\u1eb7c c\u1ee5m t\u1eeb \u1edf c\u1ed9t b\u00ean tr\u00e1i v\u1edbi c\u1ed9t b\u00ean ph\u1ea3i \u0111\u1ec3 \u0111\u01b0\u1ee3c c\u00e2u ho\u00e0n ch\u1ec9nh","audio":"","temp":"matching","correct":[["1","3","2","4"]],"list":[{"point":5,"left":["S\u1ed1 \u0111o g\u00f3c n\u1ed9i ti\u1ebfp ","S\u1ed1 \u0111o g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n","S\u1ed1 \u0111o g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m trong \u0111\u01b0\u1eddng tr\u00f2n","S\u1ed1 \u0111o g\u00f3c \u1edf t\u00e2m"],"right":["B\u1eb1ng n\u1eeda s\u1ed1 \u0111o cung b\u1ecb ch\u1eafn","B\u1eb1ng n\u1eeda t\u1ed5ng s\u1ed1 \u0111o hai cung b\u1ecb ch\u1eafn","B\u1eb1ng n\u1eeda hi\u1ec7u s\u1ed1 \u0111o hai cung b\u1ecb ch\u1eafn","B\u1eb1ng s\u1ed1 \u0111o cung b\u1ecb ch\u1eafn"],"top":100,"explain":"<span class='basic_left'> Ta c\u00f3: <br\/> S\u1ed1 \u0111o g\u00f3c n\u1ed9i ti\u1ebfp b\u1eb1ng m\u1ed9t n\u1eeda s\u1ed1 \u0111o cung b\u1ecb ch\u1eafn (\u0111\u1ecbnh l\u00ed g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> S\u1ed1 \u0111o g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m trong \u0111\u01b0\u1eddng tr\u00f2n b\u1eb1ng n\u1eeda t\u1ed5ng s\u1ed1 \u0111o hai cung b\u1ecb ch\u1eafn (\u0111\u1ecbnh l\u00ed g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n) <br\/> S\u1ed1 \u0111o g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n b\u1eb1ng n\u1eeda hi\u1ec7u s\u1ed1 \u0111o hai cung b\u1ecb ch\u1eafn (\u0111\u1ecbnh l\u00ed g\u00f3c c\u00f3 \u0111\u1ec9nh n\u1eb1m trong \u0111\u01b0\u1eddng tr\u00f2n) <br\/> S\u1ed1 \u0111o g\u00f3c \u1edf t\u00e2m b\u1eb1ng s\u1ed1 \u0111o cung b\u1ecb ch\u1eafn (\u0111\u1ecbnh l\u00ed g\u00f3c \u1edf t\u00e2m)"}]}],"id_ques":1628},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"\u0110\u1ed9 d\u00e0i cung ${{90}^{o}}$ c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 b\u00e1n k\u00ednh $\\sqrt{2}cm$ l\u00e0:","select":["A. $\\dfrac{\\sqrt{2}}{2}\\pi \\,\\left( cm \\right)$","B. $\\dfrac{1}{\\pi\\sqrt{2}} \\,\\left( cm \\right)$","C. $\\dfrac{1}{2}\\pi \\,\\left( cm \\right)$ ","D. $\\dfrac{\\sqrt{2}}{2}\\,\\left( cm \\right)$"],"explain":" <span class='basic_left'> \u0110\u1ed9 d\u00e0i cung ${{90}^{o}}$ c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 b\u00e1n k\u00ednh $\\sqrt{2}cm$ l\u00e0: <br\/> $l=\\dfrac{\\pi Rn}{180}=\\dfrac{\\pi .\\sqrt{2}.90}{180}=\\dfrac{\\pi \\sqrt{2}}{2}\\,\\left( cm \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A <\/span><\/span>","column":2}]}],"id_ques":1629},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n $(O)$ b\u00e1n k\u00ednh $R=2cm$ l\u1ea5y hai \u0111i\u1ec3m $A$ v\u00e0 $B$ sao cho $\\widehat{AOB}={{75}^{o}}.$ Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n t\u1ea1o b\u1edfi cung nh\u1ecf $AB$ l\u00e0:","select":["A. $\\dfrac{7\\pi }{3}\\,\\left( c{{m}^{2}} \\right)$","B. $\\dfrac{5\\pi }{6}\\,\\left( c{{m}^{2}} \\right)$ ","C. $\\dfrac{19\\pi }{9}\\,\\left( c{{m}^{2}} \\right)$","D. $\\dfrac{13\\pi }{6}\\,\\left( c{{m}^{2}} \\right)$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D10.png' \/><\/center> <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $2cm$ cung ${{75}^{o}}$ l\u00e0: <br\/> $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi .4.75}{360}=\\dfrac{5\\pi }{6}\\,\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B <\/span><\/span>","column":4}]}],"id_ques":1630},{"time":24,"part":[{"time":3,"title":"<span class='basic_left'> Cho tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $A$. Tr\u00ean $AC$ l\u1ea5y m\u1ed9t \u0111i\u1ec3m $M$ v\u00e0 v\u1ebd \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $MC$. K\u1ebb $BM$ c\u1eaft \u0111\u01b0\u1eddng tr\u00f2n t\u1ea1i $D$. <br\/> <b> C\u00e2u 1: <\/b> Ch\u1ee9ng minh $ABCD$ l\u00e0 m\u1ed9t t\u1ee9 gi\u00e1c n\u1ed9i ti\u1ebfp","title_trans":"S\u1eafp x\u1ebfp c\u00e1c c\u00e2u \u0111\u1ec3 \u0111\u01b0\u1ee3c b\u00e0i ch\u1ee9ng minh","temp":"sequence","correct":[[[2],[4],[1],[3]]],"list":[{"point":5,"left":["$\\widehat{BAC}={{90}^{o}}$ (gi\u1ea3 thi\u1ebft)","$\\Rightarrow$ T\u1ee9 gi\u00e1c $ABCD$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft)"," Ta c\u00f3: $\\widehat{MDC}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n)"," $\\Rightarrow$ T\u1ee9 gi\u00e1c $ABCD$ c\u00f3 hai \u0111\u1ec9nh $A$ v\u00e0 $D$ c\u00f9ng nh\u00ecn c\u1ea1nh $BC$ d\u01b0\u1edbi m\u1ed9t g\u00f3c ${{90}^{o}}$"],"top":100,"explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D11.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{MDC}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) <br\/> $\\widehat{BAC}={{90}^{o}}$ (gi\u1ea3 thi\u1ebft) <br\/> $\\Rightarrow$ T\u1ee9 gi\u00e1c $ABCD$ c\u00f3 hai \u0111\u1ec9nh $A$ v\u00e0 $D$ c\u00f9ng nh\u00ecn c\u1ea1nh $BC$ d\u01b0\u1edbi m\u1ed9t g\u00f3c ${{90}^{o}}$ <br\/> $\\Rightarrow$ T\u1ee9 gi\u00e1c $ABCD$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <\/span>"}]}],"id_ques":1631},{"time":24,"part":[{"time":3,"title":"<span class='basic_left'> Cho tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $A$. Tr\u00ean $AC$ l\u1ea5y m\u1ed9t \u0111i\u1ec3m $M$ v\u00e0 v\u1ebd \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $MC$. K\u1ebb $BM$ c\u1eaft \u0111\u01b0\u1eddng tr\u00f2n t\u1ea1i $D$. <br\/> <b> C\u00e2u 2: <\/b> \u0110\u01b0\u1eddng th\u1eb3ng $DA$ c\u1eaft \u0111\u01b0\u1eddng tr\u00f2n t\u1ea1i $S$. Ch\u1ee9ng minh $CA$ l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $SCB$. ","title_trans":"S\u1eafp x\u1ebfp c\u00e1c c\u00e2u \u0111\u1ec3 \u0111\u01b0\u1ee3c b\u00e0i ch\u1ee9ng minh","temp":"sequence","correct":[[[2],[5],[4],[1],[3]]],"list":[{"point":5,"left":["$\\Rightarrow \\widehat{{{D}_{1}}}=\\widehat{{{C}_{1}}}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn $\\overset\\frown{AB}$)","$\\Rightarrow CA$ l\u00e0 tia ph\u00e2n gi\u00e1c $\\widehat{SCB}$","$\\Rightarrow \\widehat{{{C}_{1}}}=\\widehat{{{C}_{2}}}$"," Theo c\u00e2u 1, ta c\u00f3: $ABCD$ l\u00e0 t\u1ee9 gi\u00e1c n\u1ed9i ti\u1ebfp"," M\u1eb7t kh\u00e1c $\\widehat{{{D}_{1}}}=\\widehat{{{C}_{2}}}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn $\\overset\\frown{MS}$)"],"top":100,"explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D12.png' \/><\/center> <br\/> Theo c\u00e2u 1, ta c\u00f3: $ABCD$ l\u00e0 t\u1ee9 gi\u00e1c n\u1ed9i ti\u1ebfp <br\/> $\\Rightarrow \\widehat{{{D}_{1}}}=\\widehat{{{C}_{1}}}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn $\\overset\\frown{AB}$) <br\/> M\u1eb7t kh\u00e1c $\\widehat{{{D}_{1}}}=\\widehat{{{C}_{2}}}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn $\\overset\\frown{MS}$) <br\/> $\\Rightarrow \\widehat{{{C}_{1}}}=\\widehat{{{C}_{2}}}$ <br\/> $\\Rightarrow CA$ l\u00e0 tia ph\u00e2n gi\u00e1c $\\widehat{SCB}$ <\/span>"}]}],"id_ques":1632},{"time":24,"part":[{"time":3,"title":"<span class='basic_left'>Cho n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n $(O)$ \u0111\u01b0\u1eddng k\u00ednh $AB, C$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa c\u1ee7a cung $AB, M$ l\u00e0 m\u1ed9t \u0111i\u1ec3m tr\u00ean cung $BC$. Qua $C$ k\u1ebb $CN\\bot AM$. Ch\u1ee9ng minh $\\widehat{OCN}=\\widehat{OMN}.$","title_trans":"S\u1eafp x\u1ebfp c\u00e1c c\u00e2u \u0111\u1ec3 \u0111\u01b0\u1ee3c b\u00e0i ch\u1ee9ng minh","temp":"sequence","correct":[[[4],[6],[1],[3],[5],[2]]],"list":[{"point":5,"left":[" $\\Rightarrow \\widehat{OAN}=\\widehat{OCN}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t cung) (1)","T\u1eeb (1) v\u00e0 (2) $\\Rightarrow \\widehat{OCN}=\\widehat{OMN}$","Ta c\u00f3: $C$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa cung $AB$ $\\Rightarrow OC\\bot AB$ (\u0111\u1ecbnh l\u00ed \u0111\u01b0\u1eddng k\u00ednh v\u00e0 d\u00e2y cung) $\\Rightarrow \\widehat{AOC}={{90}^{o}}$","$\\Rightarrow $ C\u00e1c \u0111i\u1ec3m $O,\\,N$ c\u00f9ng nh\u00ecn $AC$ d\u01b0\u1edbi m\u1ed9t g\u00f3c vu\u00f4ng $\\Rightarrow $ T\u1ee9 gi\u00e1c $AONC$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft)","L\u1ea1i c\u00f3: $OA=OM$ (c\u00f9ng b\u1eb1ng b\u00e1n k\u00ednh $(O)$) $\\Rightarrow \\Delta OAM$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) $\\Rightarrow \\widehat{OAM}=\\widehat{OMA}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c c\u00e2n) (2)"," M\u00e0 $CN\\bot AM$ (gi\u1ea3 thi\u1ebft) $\\Rightarrow \\widehat{ANC}={{90}^{o}}$"],"top":100,"explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D13.png' \/><\/center> <br\/> Ta c\u00f3: $C$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa cung $AB$ <br\/> $\\Rightarrow OC\\bot AB$ (\u0111\u1ecbnh l\u00ed \u0111\u01b0\u1eddng k\u00ednh v\u00e0 d\u00e2y cung) <br\/> $\\Rightarrow \\widehat{AOC}={{90}^{o}}$ <br\/> M\u00e0 $CN\\bot AM$ (gi\u1ea3 thi\u1ebft) <br\/> $\\Rightarrow \\widehat{ANC}={{90}^{o}}$ <br\/> $\\Rightarrow $ C\u00e1c \u0111i\u1ec3m $O,\\,N$ c\u00f9ng nh\u00ecn $AC$ d\u01b0\u1edbi m\u1ed9t g\u00f3c vu\u00f4ng <br\/> $\\Rightarrow $ T\u1ee9 gi\u00e1c $AONC$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <br\/> $\\Rightarrow \\widehat{OAN}=\\widehat{OCN}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t cung) (1) <br\/> L\u1ea1i c\u00f3: $OA=OM$ (c\u00f9ng b\u1eb1ng b\u00e1n k\u00ednh $(O)$) <br\/> $\\Rightarrow \\Delta OAM$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) <br\/> $\\Rightarrow \\widehat{OAM}=\\widehat{OMA}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c c\u00e2n) (2) <br\/> T\u1eeb (1) v\u00e0 (2) $\\Rightarrow \\widehat{OCN}=\\widehat{OMN}$ <\/span>"}]}],"id_ques":1633},{"time":24,"part":[{"time":3,"title":"<span class='basic_left'> Cho hai \u0111\u01b0\u1eddng tr\u00f2n$(O)$ v\u00e0 $(O\u2019)$ c\u1eaft nhau t\u1ea1i $A$ v\u00e0 $B$. V\u1ebd c\u00e1c \u0111\u01b0\u1eddng k\u00ednh $AOC$ v\u00e0 $AO\u2019D$. \u0110\u01b0\u1eddng th\u1eb3ng $AC$ c\u1eaft $(O\u2019)$ t\u1ea1i $E$. \u0110\u01b0\u1eddng th\u1eb3ng $AD$ c\u1eaft $(O)$ t\u1ea1i $F$. Ch\u1ee9ng minh r\u1eb1ng t\u1ee9 gi\u00e1c $CDEF$ n\u1ed9i ti\u1ebfp m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n.","title_trans":"S\u1eafp x\u1ebfp c\u00e1c c\u00e2u \u0111\u1ec3 \u0111\u01b0\u1ee3c b\u00e0i ch\u1ee9ng minh","temp":"sequence","correct":[[[4],[2],[1],[3]]],"list":[{"point":5,"left":["$\\Rightarrow $ T\u1ee9 gi\u00e1c $CFED$ n\u1ed9i ti\u1ebfp m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft)","$\\widehat{AED}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) hay $\\widehat{CED}={{90}^{o}}$","Ta c\u00f3: $\\widehat{CFA}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) hay $\\widehat{CFD}={{90}^{o}}$"," $\\Rightarrow $ C\u00e1c \u0111i\u1ec3m $F, E$ c\u00f9ng nh\u00ecn $CD$ d\u01b0\u1edbi m\u1ed9t g\u00f3c ${{90}^{o}}$"],"top":100,"explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D14.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{CFA}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) hay $\\widehat{CFD}={{90}^{o}}$ <br\/> $\\widehat{AED}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) hay $\\widehat{CED}={{90}^{o}}$ <br\/> $\\Rightarrow $ C\u00e1c \u0111i\u1ec3m $F, E$ c\u00f9ng nh\u00ecn $CD$ d\u01b0\u1edbi m\u1ed9t g\u00f3c ${{90}^{o}}$ <br\/> $\\Rightarrow $ T\u1ee9 gi\u00e1c $CFED$ n\u1ed9i ti\u1ebfp m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <\/span>"}]}],"id_ques":1634},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'>Cho n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $BC=10cm$ v\u00e0 d\u00e2y $BA=8cm$. T\u00ednh t\u1ed5ng di\u1ec7n t\u00edch hai h\u00ecnh vi\u00ean ph\u00e2n \u0111\u01b0\u1ee3c t\u1ea1o b\u1edfi n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n v\u00e0 tam gi\u00e1c $ABC$.","select":["A. $10\\pi -24\\,\\left( c{{m}^{2}} \\right)$","B. $25\\pi +24\\,\\left( c{{m}^{2}} \\right)$","C. $\\dfrac{25}{2}\\pi -24\\,\\left( c{{m}^{2}} \\right)$ ","D. $\\dfrac{25}{2}-24\\,\\left( c{{m}^{2}} \\right)$"],"hint":"Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm b\u1eb1ng di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n tr\u1eeb \u0111i di\u1ec7n t\u00edch tam gi\u00e1c","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D15.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{BAC}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) <br\/> B\u00e1n k\u00ednh c\u1ee7a n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n l\u00e0: $R=\\dfrac{BC}{2}=\\dfrac{10}{2}=5\\,\\left( cm \\right)$ <br\/> X\u00e9t $\\Delta BAC$ vu\u00f4ng t\u1ea1i $A$ c\u00f3: <br\/> $A{{B}^{2}}+A{{C}^{2}}=B{{C}^{2}}$ (\u0111\u1ecbnh l\u00ed Pitago) <br\/> $\\Rightarrow A{{C}^{2}}=B{{C}^{2}}-A{{B}^{2}}=100-64=36$ <br\/> $\\Rightarrow AC=6\\,\\left( cm \\right)$ <br\/> Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n l\u00e0: ${{S}_{1}}=\\dfrac{1}{2}.\\pi .{{R}^{2}}=\\dfrac{25\\pi }{2}\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch tam gi\u00e1c $ABC$ l\u00e0: ${{S}_{\\Delta ABC}}=\\dfrac{1}{2}AB.AC=\\dfrac{1}{2}6.8=24\\,\\left( c{{m}^{2}} \\right)$ <br\/> T\u1ed5ng di\u1ec7n t\u00edch hai h\u00ecnh vi\u00ean ph\u00e2n l\u00e0: $S={{S}_{1}}-{{S}_{\\Delta ABC}}=\\dfrac{25\\pi }{2}-24\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C <\/span><\/span>","column":2}]}],"id_ques":1635},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'>Cho tam gi\u00e1c $ABC$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O;R)$. Bi\u1ebft $BC=2cm,\\,\\widehat{A}={{45}^{o}}$. <br\/> <b> C\u00e2u 1: <\/b> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n $(O)$ l\u00e0:","select":["A. $10\\pi \\,\\left( c{{m}^{2}} \\right)$","B. $5\\pi \\,\\left( c{{m}^{2}} \\right)$","C. $2\\pi\\,\\left( c{{m}^{2}} \\right)$ ","D. $3\\pi\\,\\left( c{{m}^{2}} \\right)$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D16.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{BOC}=2\\widehat{BAC}={{2.45}^{o}}={{90}^{o}}$ (h\u1ec7 qu\u1ea3 g\u00f3c n\u1ed9i ti\u1ebfp) <br\/> X\u00e9t $\\Delta BOC$ vu\u00f4ng t\u1ea1i $O$ c\u00f3: <br\/> $O{{B}^{2}}+O{{C}^{2}}=B{{C}^{2}}$ (\u0111\u1ecbnh l\u00ed Pitago) <br\/> $\\Rightarrow 2{{R}^{2}}=B{{C}^{2}}\\,\\left( OB=OC=R \\right)$ <br\/> $\\Rightarrow R=\\sqrt{\\dfrac{B{{C}^{2}}}{2}}=\\sqrt{\\dfrac{4}{2}}=\\sqrt{2}\\,\\left( cm \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n $(O)$ l\u00e0: $S=\\pi {{R}^{2}}=2\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C <\/span><\/span>","column":4}]}],"id_ques":1636},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'>Cho tam gi\u00e1c $ABC$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O;R)$. Bi\u1ebft $BC=2cm,\\,\\widehat{A}={{45}^{o}}$. <br\/> <b> C\u00e2u 2: <\/b> Di\u1ec7n t\u00edch h\u00ecnh vi\u00ean ph\u00e2n gi\u1edbi h\u1ea1n b\u1edfi d\u00e2y $BC$ v\u00e0 cung nh\u1ecf $BC$ l\u00e0:","select":["A. $\\dfrac{\\pi }{4}-1\\,\\left( c{{m}^{2}} \\right)$ ","B. $\\dfrac{\\pi }{4}+1\\,\\left( c{{m}^{2}} \\right)$ ","C. $\\dfrac{\\pi }{2}-1\\,\\left( c{{m}^{2}} \\right)$ ","D. $\\dfrac{\\pi }{2}+1\\,\\left( c{{m}^{2}} \\right)$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D17.png' \/><\/center> <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $\\sqrt{2}cm$, cung tr\u00f2n ${{90}^{o}}$ l\u00e0: <br\/> ${{S}_{Q}}=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi .2.90}{360}=\\dfrac{\\pi }{2}\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch tam gi\u00e1c $BOC$ l\u00e0: <br\/> ${{S}_{\\Delta BOC}}=\\dfrac{1}{2}OB.OC=\\dfrac{1}{2}.\\sqrt{2}.\\sqrt{2}=1\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh vi\u00ean ph\u00e2n c\u1ea7n t\u00ecm l\u00e0: <br\/> $S={{S}_{Q}}-{{S}_{\\Delta BOC}}=\\dfrac{\\pi }{2}-1\\,\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C <\/span><\/span>","column":2}]}],"id_ques":1637},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["45"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho tam gi\u00e1c $ABC$ vu\u00f4ng c\u00e2n t\u1ea1i $A$, \u0111i\u1ec3m $M$ chuy\u1ec3n \u0111\u1ed9ng tr\u00ean c\u1ea1nh $AC$. K\u1ebb $CH$ vu\u00f4ng g\u00f3c v\u1edbi $BM$, c\u1eaft $BA$ \u1edf $K$. <br\/> <b> C\u00e2u 1: <\/b> S\u1ed1 \u0111o g\u00f3c $AHK$ l\u00e0 _input_ $^o$","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D18.png' \/><\/center> Ta c\u00f3: $\\widehat{BAC}=\\widehat{BHC}={{90}^{o}}$ (gi\u1ea3 thi\u1ebft) <br\/> $\\Rightarrow $ C\u00e1c \u0111i\u1ec3m $A, H$ c\u00f9ng nh\u00ecn $BC$ d\u01b0\u1edbi g\u00f3c ${{90}^{o}}$ <br\/> $\\Rightarrow $ T\u1ee9 gi\u00e1c $ABCH$ n\u1ed9i ti\u1ebfp m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <br\/> $\\Rightarrow \\widehat{AHK}=\\widehat{ABC}={{45}^{o}}$ (g\u00f3c ngo\u00e0i t\u1ea1i m\u1ed9t \u0111\u1ec9nh b\u1eb1ng g\u00f3c trong c\u1ee7a \u0111\u1ec9nh \u0111\u1ed1i di\u1ec7n) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $45$ <\/span><\/span> "}]}],"id_ques":1638},{"time":24,"part":[{"time":3,"title":"<span class='basic_left'> Cho tam gi\u00e1c $ABC$ vu\u00f4ng c\u00e2n t\u1ea1i $A$, \u0111i\u1ec3m $M$ chuy\u1ec3n \u0111\u1ed9ng tr\u00ean c\u1ea1nh $AC$. K\u1ebb $CH$ vu\u00f4ng g\u00f3c v\u1edbi $BM$, c\u1eaft $BA$ \u1edf $K$. <b> C\u00e2u 2: <\/b> Ch\u1ee9ng minh h\u1ec7 th\u1ee9c $KA.KB=KH.KC$","title_trans":"S\u1eafp x\u1ebfp c\u00e1c c\u00e2u \u0111\u1ec3 \u0111\u01b0\u1ee3c b\u00e0i ch\u1ee9ng minh","temp":"sequence","correct":[[[4],[3],[2],[1]]],"list":[{"point":5,"left":["$\\Rightarrow KA.KB=KH.KC$","$\\Rightarrow \\dfrac{KA}{KC}=\\dfrac{KH}{KB}$ (hai c\u1eb7p c\u1ea1nh t\u01b0\u01a1ng \u1ee9ng t\u1ec9 l\u1ec7)","$\\Rightarrow \\Delta KAH\\sim \\Delta KCB\\,\\left( g.g \\right)$"," X\u00e9t $\\Delta KAH$ v\u00e0 $\\Delta KCB$ c\u00f3: $\\left\\{\\begin{align} & \\widehat{K} \\left( \\text{chung} \\right)\\\\ & \\widehat{AHK}=\\widehat{ABC}\\\\ \\end{align}\\right. $ "],"top":100,"explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D18.png' \/><\/center> <br\/> X\u00e9t $\\Delta KAH$ v\u00e0 $\\Delta KCB$ c\u00f3: <br\/> $\\left\\{\\begin{align} & \\widehat{K} \\, \\text{chung} \\\\ & \\widehat{AHK}=\\widehat{ABC}\\\\ \\end{align}\\right. $ <br\/> $\\Rightarrow \\Delta KAH\\sim \\Delta KCB\\,\\left( g.g \\right)$ <br\/> $\\Rightarrow \\dfrac{KA}{KC}=\\dfrac{KH}{KB}$ (hai c\u1eb7p c\u1ea1nh t\u01b0\u01a1ng \u1ee9ng t\u1ec9 l\u1ec7) <br\/> $\\Rightarrow KA.KB=KH.KC$ <\/span>"}]}],"id_ques":1639},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["45"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n $(O)$ \u0111\u01b0\u1eddng k\u00ednh $AB, C$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa c\u1ee7a cung $AB, D$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa cung $AC$, $E$ l\u00e0 giao \u0111i\u1ec3m c\u1ee7a $OC$ v\u00e0 $BD$. S\u1ed1 \u0111o g\u00f3c $DAE$ l\u00e0 _input_ $^o$","hint":"T\u00ednh s\u1ed1 \u0111o g\u00f3c $DOE$ r\u1ed3i suy ra s\u1ed1 \u0111o g\u00f3c $DAE$ qua t\u00ednh ch\u1ea5t c\u1ee7a t\u1ee9 gi\u00e1c n\u1ed9i ti\u1ebfp","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai20/lv1/img\/h938_D20.png' \/><\/center> Ta c\u00f3: $\\widehat{DOC}=\\text{s\u0111}\\overset\\frown{DC}$ (\u0111\u1ecbnh l\u00ed g\u00f3c \u1edf t\u00e2m) <br\/> $=\\dfrac{1}{2}\\text{s\u0111}\\overset\\frown{AC}$ ($D$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa cung $AC$) <br\/> $=\\dfrac{1}{2}.\\dfrac{1}{2}\\text{s\u0111}\\overset\\frown{AB}$ ($C$ l\u00e0 \u0111i\u1ec3m ch\u00ednh gi\u1eefa c\u1ee7a cung $AB$) <br\/> $=\\dfrac{1}{4}{{.180}^{o}}={{45}^{o}}$ <br\/> L\u1ea1i c\u00f3: $\\widehat{ADB}={{90}^{o}}$ (g\u00f3c n\u1ed9i ti\u1ebfp ch\u1eafn n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n) <br\/> $\\widehat{EOA}={{90}^{o}}$ (gi\u1ea3 thi\u1ebft) <br\/> $\\Rightarrow $ C\u00e1c \u0111i\u1ec3m $D, O$ c\u00f9ng nh\u00ecn $AE$ d\u01b0\u1edbi m\u1ed9t g\u00f3c vu\u00f4ng <br\/> $\\Rightarrow $ T\u1ee9 gi\u00e1c $ADEO$ n\u1ed9i ti\u1ebfp trong m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n <br\/> $\\Rightarrow \\widehat{DAE}=\\widehat{DOE}$ (hai g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn cung $\\overset\\frown{DE}$) <br\/> M\u00e0 $\\widehat{DOC}={{45}^{o}}$ (ch\u1ee9ng minh tr\u00ean) hay $\\widehat{DOE}={{45}^{o}}$ <br\/> $\\Rightarrow \\widehat{DAE}={{45}^{o}}$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $45$ <\/span><\/span> "}]}],"id_ques":1640}],"lesson":{"save":0,"level":1}}