{"segment":[{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["360"],["270"],["180"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <table><tr><td> Trong m\u1ed9t gi\u1edd, kim ph\u00fat c\u1ee7a \u0111\u1ed3ng h\u1ed3 quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng <br><\/td><td>_input_$^o$<\/td><\/tr><tr><td> Trong$\\dfrac{3}{4}$ gi\u1edd, kim ph\u00fat c\u1ee7a \u0111\u1ed3ng h\u1ed3 quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng <br><\/td><td>_input_ $^o$<\/td><\/tr><tr><td> Trong $30$ ph\u00fat, kim ph\u00fat c\u1ee7a \u0111\u1ed3ng h\u1ed3 quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng <\/td><td>_input_ $^o$<\/td><\/tr><\/table>","explain":["<span class='basic_left'> $\\bullet$ Trong m\u1ed9t gi\u1edd, kim ph\u00fat \u0111i \u0111\u01b0\u1ee3c m\u1ed9t v\u00f2ng tr\u00f2n n\u00ean n\u00f3 quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng ${{360}^{o}}$ <\/span>","<span class='basic_left'> $\\bullet$ Ta c\u00f3 m\u1ed9t gi\u1edd kim ph\u00fat quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng ${{360}^{o}}$ <br\/> $\\Rightarrow\\dfrac{3}{4}$ gi\u1edd kim ph\u00fat quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng: <br\/> $\\dfrac{3}{4}{{.360}^{o}}={{270}^{o}}$ <\/span>","<span class='basic_left'> $\\bullet$ \u0110\u1ed5i: $30$ ph\u00fat $= 0,5$ gi\u1edd. <br\/> Ta c\u00f3 m\u1ed9t gi\u1edd kim ph\u00fat quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng ${{360}^{o}}$ <br\/> $\\Rightarrow 0,5$ gi\u1edd kim ph\u00fat quay \u0111\u01b0\u1ee3c m\u1ed9t cung c\u00f3 s\u1ed1 \u0111o b\u1eb1ng: <br\/> $0,{{5.360}^{o}}={{180}^{o}}$ <\/span>"]}]}],"id_ques":1411},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["100"],["215"],["79"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <table><tr><th>Cho h\u00ecnh v\u1ebd<br><\/th><th>S\u1ed1 \u0111o cung<br><\/th><\/tr><tr><td> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D2.1.png' \/><\/center><br><\/td><td>$\\overset\\frown{AmB}=$_input_$^o$<\/td><\/tr><tr><td> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D2.2.png' \/><\/center> <br><\/td><td>$\\overset\\frown{CmD}=$_input_ $^o$<\/td><\/tr><tr><td> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D2.3.png' \/><\/center> <\/td><td>$\\overset\\frown{EmF}=$_input_ $^o$<\/td><\/tr><\/table>","explain":["<span class='basic_left'> $\\bullet$ <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D2.1.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{AOB}=100^o$ <br\/> $\\Rightarrow \\overset\\frown{AmB}= 100^o$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <\/span> ","<span class='basic_left'> $\\bullet$ <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D2.2.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{COD}=145^o$ <br\/> $\\Rightarrow \\overset\\frown{CnD}= 145^o$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> $\\Rightarrow \\overset\\frown{CmD}= 360^o - 145^o = 215^o$<span>","<span class='basic_left'> $\\bullet$ <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D2.3.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{EOF}=79^o$ <br\/> $\\Rightarrow \\overset\\frown{EmF}= 79^o$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung)<span>"]}]}],"id_ques":1412},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["115"]]],"list":[{"point":5,"width":50,"type_input":"","input_hint":["frac"],"ques":" <span class='basic_left'> Cho \u0111\u01b0\u1eddng tr\u00f2n $(O)$, hai ti\u1ebfp tuy\u1ebfn c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u1edf $A$ v\u00e0 $B$ c\u1eaft nhau \u1edf $M$ sao cho $\\widehat{AMB}$ b\u1eb1ng $65^o.$ T\u00ednh s\u1ed1 \u0111o g\u00f3c \u1edf t\u00e2m t\u1ea1o b\u1edfi hai b\u00e1n k\u00ednh $OA$ v\u00e0 $OB$. <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> S\u1ed1 \u0111o g\u00f3c c\u1ea7n t\u00ecm l\u00e0 _input_$^o$ ","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D3.png' \/><\/center> <br\/>G\u00f3c \u1edf t\u00e2m t\u1ea1o b\u1edfi hai b\u00e1n k\u00ednh $OA$ v\u00e0 $OB$ l\u00e0 $\\widehat{AOB}$ <br\/> Ta c\u00f3: $\\left\\{ \\begin{align} & \\widehat{OAM}={{90}^{o}} \\\\ & \\widehat{OBM}={{90}^{o}} \\\\ \\end{align} \\right.$ (t\u00ednh ch\u1ea5t ti\u1ebfp tuy\u1ebfn) <br\/> X\u00e9t t\u1ee9 gi\u00e1c $OAMB$ c\u00f3: <br\/> $\\widehat{OAM}+\\widehat{AMB}+\\widehat{MBO}+\\widehat{BOA}={{360}^{o}}$(t\u1ed5ng c\u00e1c g\u00f3c c\u1ee7a t\u1ee9 gi\u00e1c) <br\/> $\\Rightarrow \\widehat{BOA}={{360}^{o}}-\\left( \\widehat{OAM}+\\widehat{AMB}+\\widehat{MBO} \\right) $ <br\/> $\\hspace{1cm}\\,\\,\\,\\,\\,\\,\\,={{360}^{o}}-\\left( {{90}^{o}}+{{65}^{o}}+{{90}^{o}} \\right)={{115}^{o}}$ <br\/> Suy ra $\\widehat{AOB}={{115}^{o}}$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $115$<\/span> <\/span>"}]}],"id_ques":1413},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u (>; <; =) th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["<"]]],"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/bai13/lv1/img\/h931_D4.png' \/><\/center> <br\/> Bi\u1ebft $\\widehat{EOF}={{100}^{o}},\\widehat{AOB}={{67}^{o}}$. H\u00e3y so s\u00e1nh hai cung $AB$ v\u00e0 $EF$. <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $\\text{s\u0111}\\overset\\frown{AB}$ _input_ $\\text{s\u0111}\\overset\\frown{EF}$ ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D4.png' \/><\/center> <br\/> Ta c\u00f3: $\\left\\{ \\begin{align} & \\text{s\u0111}\\overset\\frown{EF}=\\widehat{EOF}={{100}^{o}} \\\\ & \\text{s\u0111}\\overset\\frown{AB}=\\widehat{AOB}={{67}^{o}} \\\\ \\end{align} \\right.$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AB}<\\text{s\u0111}\\overset\\frown{EF}$ <br\/> <span class='basic_pink'> V\u1eady d\u1ea5u c\u1ea7n \u0111i\u1ec1n l\u00e0 $<$ <\/span><\/span> "}]}],"id_ques":1414},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"L\u00fac $12$ gi\u1edd, kim gi\u1edd v\u00e0 kim ph\u00fat t\u1ea1o th\u00e0nh g\u00f3c bao nhi\u00eau \u0111\u1ed9? ","select":["A. ${360}^{o}$ ","B. ${180}^{o}$ ","C. ${90}^{o}$","D. ${0}^{o}$"],"explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D5.png' \/><\/center> <br\/> T\u1ea1i th\u1eddi \u0111i\u1ec3m $12$ gi\u1edd, kim gi\u1edd v\u00e0 kim ph\u00fat tr\u00f9ng nhau <br\/> N\u00ean ch\u00fang t\u1ea1o v\u1edbi nhau g\u00f3c $0^o$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D <\/span><\/span>","column":4}]}],"id_ques":1415},{"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":"Bi\u1ebft \u0111\u1ed9 d\u00e0i cung $\\overset\\frown{AmB}$ b\u1eb1ng $\\dfrac{1}{3}$ \u0111\u01b0\u1eddng tr\u00f2n. S\u1ed1 \u0111o $\\overset\\frown{AmB}$ l\u00e0 _input_$^o$","explain":" <span class='basic_left'> S\u1ed1 \u0111o c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n b\u1eb1ng $360^o$ <br\/> Cung $\\overset\\frown{AmB}$ b\u1eb1ng $\\dfrac{1}{3}$ \u0111\u01b0\u1eddng tr\u00f2n <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AmB} = \\dfrac{1}{3}.360^o=120^o$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $120$ <\/span><\/span> "}]}],"id_ques":1416},{"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":" Cho \u0111\u01b0\u1eddng tr\u00f2n $\\left( O;R \\right)$. Qua \u0111i\u1ec3m $A$ thu\u1ed9c \u0111\u01b0\u1eddng tr\u00f2n, k\u1ebb ti\u1ebfp tuy\u1ebfn $Ax$, tr\u00ean \u0111\u00f3 l\u1ea5y \u0111i\u1ec3m $B$ sao cho $OB=\\sqrt{2}R$. $OB$ c\u1eaft \u0111\u01b0\u1eddng tr\u00f2n $(O)$ \u1edf $C$. S\u1ed1 \u0111o cung nh\u1ecf $AC$ l\u00e0 _input_$^o$","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D7.png' \/><\/center> <br\/> Ta c\u00f3: $\\widehat{OAB}={{90}^{o}}$ (t\u00ednh ch\u1ea5t ti\u1ebfp tuy\u1ebfn) <br\/> X\u00e9t $\\Delta OAB$ vu\u00f4ng t\u1ea1i $A$ c\u00f3: <br\/> $O{{B}^{2}}=O{{A}^{2}}+A{{B}^{2}}$ (\u0111\u1ecbnh l\u00ed Pitago) <br\/> $\\Rightarrow A{{B}^{2}}=O{{B}^{2}}-O{{A}^{2}}={{\\left( \\sqrt{2}R \\right)}^{2}}-{{R}^{2}}={{R}^{2}}$ <br\/> $\\Rightarrow AB=OB=R$ <br\/> $\\Rightarrow \\Delta OAB$ vu\u00f4ng c\u00e2n t\u1ea1i $A$ <br\/> $\\Rightarrow \\widehat{AOB}={{45}^{o}}$ $\\Rightarrow \\text{s\u0111}\\overset\\frown{AC}={{45}^{o}}$(\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $45$ <\/span> <\/span> "}]}],"id_ques":1417},{"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 hai \u0111\u01b0\u1eddng tr\u00f2n nh\u01b0 h\u00ecnh v\u1ebd sau, <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D8.png' \/><\/center> <br\/> Bi\u1ebft s\u1ed1 \u0111o $\\overset\\frown{AnB}={{55}^{o}}$. T\u00ednh s\u1ed1 \u0111o cung $\\overset\\frown{MaN}.$ ","select":["A. L\u1edbn h\u01a1n ${{55}^{o}}$ ","B. Nh\u1ecf h\u01a1n ${{55}^{o}}$ ","C. B\u1eb1ng ${55}^{o}$","D. Kh\u00f4ng t\u00ednh \u0111\u01b0\u1ee3c"],"explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D8.png' \/><\/center> <br\/> X\u00e9t \u0111\u01b0\u1eddng tr\u00f2n nh\u1ecf, ta c\u00f3: <br\/> $\\text{s\u0111}\\overset\\frown{AnB}={{55}^{o}}$ <br\/> $\\Rightarrow \\widehat{BOA}={{55}^{o}}$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> X\u00e9t \u0111\u01b0\u1eddng tr\u00f2n l\u1edbn, ta c\u00f3: <br\/> $\\widehat{BOA}=\\widehat{MON}={{55}^{o}}$ <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{MaN}={{55}^{o}}$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C <\/span><\/span>","column":2}]}],"id_ques":1418},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Hi\u1ec7n t\u1ea1i l\u00e0 $6$ gi\u1edd s\u00e1ng. H\u1ecfi sau $2$ gi\u1edd n\u1eefa, kim gi\u1edd quay m\u1ed9t g\u00f3c bao nhi\u00eau \u0111\u1ed9? ","select":["A. ${{30}^{o}}$ ","B. ${{60}^{o}}$ ","C. ${90}^{o}$","D. $120^o$"],"explain":"<span class='basic_left'> Coi \u0111\u1ed3ng h\u1ed3 nh\u01b0 m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n <br\/> Ta c\u00f3 cung c\u1ea3 \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 s\u1ed1 \u0111o l\u00e0 ${{360}^{o}}$ <br\/> $\\Rightarrow $ M\u1ed9t gi\u1edd kim gi\u1edd quay \u0111\u01b0\u1ee3c cung c\u00f3 s\u1ed1 \u0111o l\u00e0: ${{360}^{o}}:12={{30}^{o}}$ <br\/> $\\Rightarrow $ Hai gi\u1edd kim gi\u1edd quay \u0111\u01b0\u1ee3c cung c\u00f3 s\u1ed1 \u0111o l\u00e0: ${{30}^{o}}.2={{60}^{o}}$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B <\/span><\/span>","column":4}]}],"id_ques":1419},{"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 \u0111\u01b0\u1eddng tr\u00f2n $(O; R)$ \u0111\u01b0\u1eddng k\u00ednh $AC$. Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n l\u1ea5y \u0111i\u1ec3m $B$ sao cho $\\widehat{BAC}={{50}^{o}}$. T\u00ednh s\u1ed1 \u0111o cung nh\u1ecf $BC.$ <br\/><b> \u0110\u00e1p s\u1ed1: <\/b> $\\text{s\u0111}\\overset\\frown{BC} = $ _input_ $^o$","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D10.png' \/><\/center> <br\/>X\u00e9t $\\Delta OAB$ c\u00f3: <br\/> $OA=OB=R$ <br\/> $\\Rightarrow \\Delta OAB$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) <br\/> $\\Rightarrow \\widehat{BAO}=\\widehat{ABO}={{50}^{o}}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c c\u00e2n) <br\/> M\u00e0 $\\widehat{COB}=\\widehat{OAB}+\\widehat{OBA}$ (\u0111\u1ecbnh l\u00ed g\u00f3c \u1edf ngo\u00e0i t\u1ea1i m\u1ed9t \u0111\u1ec9nh c\u1ee7a tam gi\u00e1c) <br\/> $\\Rightarrow \\widehat{COB}=2\\widehat{OAB}={{2.50}^{o}}={{100}^{o}}$ <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{BC}={{100}^{o}}$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $100$<\/span> <\/span>"}]}],"id_ques":1420},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["280"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'> Cho \u0111\u01b0\u1eddng tr\u00f2n $(O; R)$ \u0111\u01b0\u1eddng k\u00ednh $AC$. Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n l\u1ea5y \u0111i\u1ec3m $B$ sao cho $\\widehat{BAC}={{50}^{o}}$. T\u00ednh s\u1ed1 \u0111o cung l\u1edbn $AB$. <br\/><b> \u0110\u00e1p s\u1ed1: <\/b> S\u1ed1 \u0111o cung l\u1edbn $AB$ l\u00e0 _input_ $^o$","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D10.png' \/><\/center> <br\/>X\u00e9t $\\Delta OAB$ c\u00f3: <br\/> $OA=OB=R$ <br\/> $\\Rightarrow \\Delta OAB$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) <br\/> $\\Rightarrow \\widehat{BAO}=\\widehat{ABO}={{50}^{o}}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c c\u00e2n) <br\/> M\u00e0 $\\widehat{OAB}+\\widehat{OBA}+\\widehat{AOB}={{180}^{o}}$ (t\u1ed5ng ba g\u00f3c c\u1ee7a tam gi\u00e1c) <br\/> $\\Rightarrow \\widehat{AOB}={{180}^{o}}-\\left( \\widehat{OAB}+\\widehat{OBA} \\right)$ <br\/> $\\hspace{1cm} \\,\\,\\,\\,\\,\\,\\,={{180}^{o}}-\\left( {{50}^{o}}+{{50}^{o}} \\right)={{80}^{o}}$ <br\/> $\\Rightarrow $ S\u1ed1 \u0111o cung nh\u1ecf $AB$ l\u00e0: $\\text{s\u0111}\\overset\\frown{AB}=\\widehat{AOB}={{80}^{o}}$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> $\\Rightarrow $ S\u1ed1 \u0111o cung l\u1edbn $AB$ l\u00e0: ${{360}^{o}}-{{80}^{o}}={{280}^{o}}$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $280$<\/span> <\/span>"}]}],"id_ques":1421},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["110"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'> Cho tam gi\u00e1c $ABC$ c\u00f3 g\u00f3c $A$ b\u1eb1ng $70^o$. \u0110\u01b0\u1eddng tr\u00f2n $(O)$ n\u1ed9i ti\u1ebfp tam gi\u00e1c v\u00e0 ti\u1ebfp x\u00fac v\u1edbi c\u00e1c c\u1ea1nh $AB,\\,AC$ t\u1ea1i $D$ v\u00e0 $E$. T\u00ednh s\u1ed1 \u0111o cung nh\u1ecf $DE.$ <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> S\u1ed1 \u0111o $\\overset\\frown{DE}$ l\u00e0 _input_ $^o$","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D12.png' \/><\/center> <br\/>Ta c\u00f3: $AB; AC$ l\u00e0 c\u00e1c ti\u1ebfp tuy\u1ebfn c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n $(O)$ <br\/> $\\Rightarrow \\widehat{ODA}=\\widehat{OEA}={{90}^{o}}$ (t\u00ednh ch\u1ea5t ti\u1ebfp tuy\u1ebfn) <br\/> X\u00e9t t\u1ee9 gi\u00e1c $ODAE$ c\u00f3: <br\/> $\\widehat{ODA}+\\widehat{DAE}+\\widehat{AEO}+\\widehat{EOD}={{360}^{o}}$ (t\u1ed5ng c\u00e1c g\u00f3c c\u1ee7a t\u1ee9 gi\u00e1c) <br\/> $\\Rightarrow \\widehat{EOD}={{360}^{o}}-\\left( \\widehat{ODA}+\\widehat{DAE}+\\widehat{AEO} \\right)$ <br\/> $\\hspace{1cm}\\,\\,\\,\\,\\,\\,\\,\\,={{360}^{o}}-\\left( {{90}^{o}}+{{70}^{o}}+{{90}^{o}} \\right)={{110}^{o}}$ <br\/> Suy ra g\u00f3c $\\widehat{EOD}={{110}^{o}}$ <br\/> Hay s\u1ed1 \u0111o cung nh\u1ecf $DE$ b\u1eb1ng $110^o$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $110$<\/span> <\/span>"}]}],"id_ques":1422},{"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 \u0111\u01b0\u1eddng tr\u00f2n $(O;R)$, hai d\u00e2y cung $AB$ v\u00e0 $MC$ c\u1eaft nhau t\u1ea1i $O$. Bi\u1ebft $\\widehat{AMO}={{30}^{o}}$, s\u1ed1 \u0111o cung nh\u1ecf $BC$ l\u00e0 _input_$^o$","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D13.png' \/><\/center> <br\/> X\u00e9t $\\Delta OAM$ c\u00f3: <br\/> $OA=OM=R$ <br\/> $\\Rightarrow \\Delta OAM$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) <br\/> $\\Rightarrow \\widehat{OAM}=\\widehat{OMA}={{30}^{o}}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c c\u00e2n) <br\/> M\u00e0 $\\widehat{OAM}+\\widehat{OMA}+\\widehat{AOM}={{180}^{o}}$ (t\u1ed5ng ba g\u00f3c trong tam gi\u00e1c) <br\/> $\\Rightarrow \\widehat{AOM}={{180}^{o}}-\\left( \\widehat{OAM}+\\widehat{OMA} \\right)$ <br\/> $\\hspace{1cm}\\,\\,\\,\\,\\,\\,\\,\\,={{180}^{o}}-\\left( {{30}^{o}}+{{30}^{o}} \\right)={{120}^{o}}$ <br\/> $\\Rightarrow \\widehat{BOC}=\\widehat{AOM}={{120}^{o}}$ (hai g\u00f3c \u0111\u1ed1i \u0111\u1ec9nh) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{BC}= 120^o$<br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $120$ <\/span><\/span> "}]}],"id_ques":1423},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0110\u00fang hay Sai","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"Trong \u0111\u01b0\u1eddng tr\u00f2n $(O;R)$ v\u1ebd d\u00e2y $AB$ c\u00f3 \u0111\u1ed9 d\u00e0i b\u1eb1ng $R$. Khi \u0111\u00f3, cung nh\u1ecf $AB$ c\u00f3 s\u1ed1 \u0111o b\u1eb1ng $60^o$ ","select":["A. \u0110\u00fang ","B. Sai "],"explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D14.png' \/><\/center> <br\/> X\u00e9t $\\Delta OAB$ c\u00f3: <br\/> $OA=OB=AB=R$ <br\/> $\\Rightarrow \\Delta OAB$ \u0111\u1ec1u (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c \u0111\u1ec1u) <br\/> $\\Rightarrow \\widehat{AOB}={{60}^{o}}$ (t\u00ednh ch\u1ea5t tam gi\u00e1c \u0111\u1ec1u) <br\/> S\u1ed1 \u0111o cung nh\u1ecf $AB$ b\u1eb1ng $60^o$. <br\/> Suy ra kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 \u0111\u00fang <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A <\/span><\/span>","column":2}]}],"id_ques":1424},{"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 \u0111\u01b0\u1eddng tr\u00f2n $(O)$, v\u1ebd d\u00e2y $AB$ sao cho s\u1ed1 \u0111o c\u1ee7a cung nh\u1ecf $AB$ b\u1eb1ng m\u1ed9t n\u1eeda s\u1ed1 \u0111o c\u1ee7a cung l\u1edbn $AB$. S\u1ed1 \u0111o c\u1ee7a cung nh\u1ecf $AB$ l\u00e0 _input_$^o$","explain":"<span class='basic_left'>Ta c\u00f3 cung c\u1ea3 \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 s\u1ed1 \u0111o l\u00e0 $360^o$ <br\/> Do s\u1ed1 \u0111o c\u1ee7a cung nh\u1ecf $AB$ b\u1eb1ng m\u1ed9t n\u1eeda s\u1ed1 \u0111o c\u1ee7a cung l\u1edbn $AB$ <br\/> N\u00ean s\u1ed1 \u0111o c\u1ee7a cung nh\u1ecf $AB$ b\u1eb1ng $\\dfrac{1}{3}$ s\u1ed1 \u0111o c\u1ee7a cung c\u1ea3 \u0111\u01b0\u1eddng tr\u00f2n <br\/> Suy ra s\u1ed1 \u0111o c\u1ee7a cung nh\u1ecf $AB$ l\u00e0: <br\/> ${{360}^{o}}:3={{120}^{o}}$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $120$ <\/span> <\/span> "}]}],"id_ques":1425},{"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 \u0111\u01b0\u1eddng tr\u00f2n $(O)$, c\u00e1c \u0111i\u1ec3m $A, B, C$ n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n. Bi\u1ebft $\\text{s\u0111}\\overset\\frown{AB}={{100}^{o}}$; $\\text{s\u0111}\\overset\\frown{BC}={{60}^{o}}$. S\u1ed1 \u0111o g\u00f3c \u1edf t\u00e2m $\\widehat{AOC}$ l\u00e0: ","select":["A. ${{40}^{o}}$ ","B. ${{160}^{o}}$ ","C. ${40}^{o}$ ho\u1eb7c ${160}^{o}$","D. ${200}^{o}$"],"explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D16.png' \/><\/center> <br\/> Tr\u01b0\u1eddng h\u1ee3p 1: \u0110i\u1ec3m $C$ n\u1eb1m trong cung nh\u1ecf $AB$ <br\/> Khi \u0111\u00f3: $\\text{s\u0111}\\overset\\frown{AC}+\\text{s\u0111}\\overset\\frown{CB}=\\text{s\u0111}\\overset\\frown{AB}$ (do $C$ n\u1eb1m gi\u1eefa $A$ v\u00e0 $B$) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AC}=\\text{s\u0111}\\overset\\frown{AB}-\\text{s\u0111}\\overset\\frown{BC}={{100}^{o}}-{{60}^{o}}={{40}^{o}}$ <br\/> Tr\u01b0\u1eddng h\u1ee3p 2: \u0110i\u1ec3m $C$ n\u1eb1m tr\u00ean cung l\u1edbn $AB$ <br\/> Khi \u0111\u00f3: $\\text{s\u0111}\\overset\\frown{AB}+\\text{s\u0111}\\overset\\frown{BC}=\\text{s\u0111}\\overset\\frown{AC}$ (do $B$ n\u1eb1m gi\u1eefa $A$ v\u00e0 $C$) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AC}={{100}^{o}}+{{60}^{o}}={{160}^{o}}$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C <\/span><\/span>","column":2}]}],"id_ques":1426},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"N\u1ebfu $C$ l\u00e0 m\u1ed9t \u0111i\u1ec3m n\u1eb1m tr\u00ean cung $AB$ th\u00ec: ","select":["A. $\\text{s\u0111}\\overset\\frown{AB}+\\text{s\u0111}\\overset\\frown{BC}=\\text{s\u0111}\\overset\\frown{AC}$ ","B. $\\text{s\u0111}\\overset\\frown{AC}+\\text{s\u0111}\\overset\\frown{CB}=\\text{s\u0111}\\overset\\frown{AB}$ ","C. $\\text{s\u0111}\\overset\\frown{BA}+\\text{s\u0111}\\overset\\frown{AC}=\\text{s\u0111}\\overset\\frown{BC}$"],"explain":" Theo \u0111\u1ecbnh l\u00ed (trang 68 \u2013 s\u00e1ch gi\u00e1o khoa) N\u1ebfu $C$ l\u00e0 m\u1ed9t \u0111i\u1ec3m n\u1eb1m tr\u00ean cung $AB$ th\u00ec: <br\/> $\\text{s\u0111}\\overset\\frown{AC}+\\text{s\u0111}\\overset\\frown{CB}=\\text{s\u0111}\\overset\\frown{AB}$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B <\/span>","column":1}]}],"id_ques":1427},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u (>; <; =) th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["="]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'> Cho hai \u0111\u01b0\u1eddng tr\u00f2n \u0111\u1ed3ng t\u00e2m $\\left( O;R \\right)$ v\u00e0 $\\left( O;\\,R\\sqrt{3} \\right)$. Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n nh\u1ecf l\u1ea5y \u0111i\u1ec3m $M$, ti\u1ebfp tuy\u1ebfn t\u1ea1i $M$ c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n nh\u1ecf c\u1eaft \u0111\u01b0\u1eddng tr\u00f2n l\u1edbn t\u1ea1i $A$ v\u00e0 $B$. Tia $OM$ c\u1eaft \u0111\u01b0\u1eddng tr\u00f2n l\u1edbn t\u1ea1i $C$. H\u00e3y so s\u00e1nh s\u1ed1 \u0111o hai cung $AC$ v\u00e0 $BC$. <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $\\text{s\u0111}\\overset\\frown{AC}$ _input_ $\\text{s\u0111}\\overset\\frown{BC}$ ","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D18.png' \/><\/center> <br\/>X\u00e9t $\\Delta OAB$ c\u00f3: <br\/> $OA=OB=R\\sqrt{3}$ <br\/> $\\Rightarrow \\Delta OAB$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) <br\/> M\u00e0 $OM\\bot AB$ (t\u00ednh ch\u1ea5t ti\u1ebfp tuy\u1ebfn) <br\/> $\\Rightarrow OM$ l\u00e0 ph\u00e2n gi\u00e1c c\u1ee7a $\\widehat{AOB}$ <br\/> $\\Rightarrow \\widehat{AOC}=\\widehat{BOC}$ (t\u00ednh ch\u1ea5t \u0111\u01b0\u1eddng ph\u00e2n gi\u00e1c) <br\/> L\u1ea1i c\u00f3: $\\left\\{ \\begin{align} & \\text{s\u0111}\\overset\\frown{AC}=\\widehat{AOC} \\\\ & \\text{s\u0111}\\overset\\frown{BC}=\\widehat{BOC} \\\\ \\end{align} \\right.$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AC}=\\text{s\u0111}\\overset\\frown{BC}$ <br\/> <span class='basic_pink'> V\u1eady d\u1ea5u c\u1ea7n \u0111i\u1ec1n l\u00e0 $=$<\/span> <\/span>"}]}],"id_ques":1428},{"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 \u0111\u01b0\u1eddng tr\u00f2n $(O; R)$, v\u1ebd d\u00e2y $AB$ sao cho $AB=R\\sqrt{3}.$ T\u00ednh s\u1ed1 \u0111o cung nh\u1ecf $AB$. <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $\\text{s\u0111}\\overset\\frown{AB}=$ _input_$^o$","explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D19.png' \/><\/center> <br\/> K\u1ebb $OH\\bot AB$ <br\/> $\\Rightarrow HA = HB$ (\u0111\u1ecbnh l\u00ed \u0111\u01b0\u1eddng k\u00ednh v\u00e0 d\u00e2y cung) <br\/> $\\Rightarrow HA=\\dfrac{AB}{2}=\\dfrac{R\\sqrt{3}}{2}$ <br\/> X\u00e9t $\\Delta AHO$ vu\u00f4ng t\u1ea1i $H$ ta c\u00f3: <br\/> $\\sin \\widehat{AOH}=\\dfrac{AH}{OA}=\\dfrac{\\dfrac{R\\sqrt{3}}{2}}{R}=\\dfrac{\\sqrt{3}}{2}$ <br\/> $\\Rightarrow \\widehat{AOH}={{60}^{o}}$ <br\/> T\u01b0\u01a1ng t\u1ef1 ta t\u00ednh \u0111\u01b0\u1ee3c: $\\widehat{BOH}={{60}^{o}}$ <br\/> $\\Rightarrow \\widehat{AOB}=\\widehat{AOH}+\\widehat{BOH}={{60}^{o}}+{{60}^{o}}={{120}^{o}}$ <br\/> $\\Rightarrow \\text{s\u0111}\\overset\\frown{AB}={{120}^{o}}$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $120$ <\/span> <\/span> "}]}],"id_ques":1429},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"Cho $EF$ l\u00e0 d\u00e2y cung c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n $\\left( O;R \\right)$. Bi\u1ebft $\\text{s\u0111}\\overset\\frown{EF}={{60}^{o}}.$ T\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y $EF$ theo $R$. ","select":["A. $EF=R$ ","B. $EF=R\\sqrt{2}$ ","C. $EF=R\\sqrt{3}$","D. $EF=\\dfrac{R\\sqrt{2}}{2}$"],"explain":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai13/lv1/img\/h931_D20.png' \/><\/center> <br\/> X\u00e9t $\\Delta OEF$ c\u00f3: <br\/> $OE = OF = R$ <br\/> $\\Rightarrow \\Delta OEF$ c\u00e2n t\u1ea1i $O$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n) <br\/> M\u00e0 $\\text{s\u0111}\\overset\\frown{EF}={{60}^{o}}\\Rightarrow \\widehat{EOF}={{60}^{o}}$ (\u0111\u1ecbnh ngh\u0129a s\u1ed1 \u0111o cung) <br\/> $\\Rightarrow \\Delta OEF$ \u0111\u1ec1u (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <br\/> $\\Rightarrow EF=R$ (\u0111\u1ecbnh ngh\u0129a tam gi\u00e1c \u0111\u1ec1u) <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A <\/span><\/span>","column":4}]}],"id_ques":1430}],"lesson":{"save":0,"level":1}}