{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{C}=50^o;\\widehat{D}=70^o$. G\u1ecdi $E$ l\u00e0 giao \u0111i\u1ec3m c\u1ee7a c\u00e1c ph\u00e2n gi\u00e1c trong g\u00f3c $A$ v\u00e0 g\u00f3c $B$. S\u1ed1 \u0111o $\\widehat{AEB}$ l\u00e0: <\/span>","select":[" A. $ 40^o$"," B. $50^o$","C. $60^o$","D. $70^o$"],"Hint":"T\u00ecm t\u1ed5ng hai g\u00f3c $A$ v\u00e0 $B$ c\u1ee7a t\u1ee9 gi\u00e1c $ABCD$. <br\/> X\u00e9t trong tam gi\u00e1c $ABE$ \u0111\u1ec3 t\u00ecm s\u1ed1 \u0111o g\u00f3c $AEB$.","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_1.jpg' \/><\/center> T\u1ee9 gi\u00e1c $ABCD$ c\u00f3: <br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}=360^o$ (\u0110\u1ecbnh l\u00ed t\u1ed5ng b\u1ed1n g\u00f3c trong t\u1ee9 gi\u00e1c) <br\/> $\\Rightarrow \\widehat{A}+\\widehat{B}+50^o+70^o=360^o$ <br\/> $\\widehat{A}+\\widehat{B}=360^o-120^o$ <br\/> $\\widehat{A}+\\widehat{B}=240^o$ <br\/> M\u00e0 $AE$ v\u00e0 $BE$ l\u1ea7n l\u01b0\u1ee3t l\u00e0 c\u00e1c ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $A$ v\u00e0 $B$ n\u00ean: <br\/> $\\widehat{A_1}+\\widehat{B_1}$$=\\dfrac{\\widehat{A}+\\widehat{B}}{2}=\\dfrac{240^o}{2}=120^o$ <br\/> X\u00e9t $\\Delta ABE$ c\u00f3: $\\widehat{A_1}+\\widehat{B_1}+\\widehat{AEB}=180^o$ <br\/> $\\Rightarrow 120^o+\\widehat{AEB}=180^o$ <br\/> $\\Rightarrow \\widehat{AEB}=180^o-120^o=60^o$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C. <\/span><\/span> ","column":4}]}],"id_ques":1521},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}:\\widehat{B}:\\widehat{C}:\\widehat{D}=2:4:6:8$ <br\/> S\u1ed1 \u0111o c\u00e1c g\u00f3c c\u1ee7a t\u1ee9 gi\u00e1c $ABCD$ l\u00e0: <\/span>","select":[" A. $ 34^o; 102^o; 68^o; 136^o$"," B. $36^o; 72^o; 108^o; 144^o$","C. $32^o; 64^o; 96^o; 128^o$","D. $38^o; 76^o; 114^o; 152$"],"Hint":"T\u1eeb t\u1ec9 l\u1ec7 \u0111\u1ec1 b\u00e0i cho \u0111\u01b0a v\u1ec1 d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau r\u1ed3i t\u00ecm s\u1ed1 \u0111o c\u00e1c g\u00f3c $A, B, C, D$.","explain":" <span class='basic_left'> T\u1ee9 gi\u00e1c $ABCD$ c\u00f3: <br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}=360^o$ (\u0111\u1ecbnh l\u00ed t\u1ed5ng c\u00e1c g\u00f3c trong t\u1ee9 gi\u00e1c) <br\/> M\u00e0 theo b\u00e0i c\u00f3: $\\widehat{A}:\\widehat{B}:\\widehat{C}:\\widehat{D}=2:4:6:8$ <br\/> $\\Rightarrow \\dfrac{\\widehat{A}}{2}=\\dfrac{\\widehat{B}}{4}=\\dfrac{\\widehat{C}}{6}=\\dfrac{\\widehat{D}}{8}$$=\\dfrac{\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}}{2+4+6+8}$$=\\dfrac{{{360}^{o}}}{20}={{18}^{o}}$ <br\/> (t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau)<br\/> $\\Rightarrow \\left\\{ \\begin{align} & \\widehat{A}={{2.18}^{o}}={{36}^{o}} \\\\ & \\widehat{B}={{4.18}^{o}}={{72}^{o}} \\\\ & \\widehat{C}={{6.18}^{o}}={{108}^{o}} \\\\ & \\widehat{D}={{8.18}^{o}}={{144}^{o}} \\\\ \\end{align} \\right.$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1522},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> T\u1ec9 s\u1ed1 \u0111\u1ed9 d\u00e0i hai c\u1ea1nh c\u1ee7a m\u1ed9t h\u00ecnh b\u00ecnh h\u00e0nh l\u00e0 $3 : 4$, c\u00f2n chu vi c\u1ee7a n\u00f3 b\u1eb1ng $2,8\\, cm$. \u0110\u1ed9 d\u00e0i hai c\u1ea1nh k\u1ec1 c\u1ee7a h\u00ecnh b\u00ecnh h\u00e0nh l\u00e0: <\/span>","select":[" A. $4,5\\, cm$ v\u00e0 $6\\, cm$"," B. $0,6\\, cm$ v\u00e0 $0,8\\, cm$","C. $0,2\\, cm$ v\u00e0 $0,5\\, cm$","D. \u0110\u00e1p \u00e1n kh\u00e1c"],"explain":" <span class='basic_left'> G\u1ecdi \u0111\u1ed9 d\u00e0i hai c\u1ea1nh c\u1ea7n t\u00ecm l\u00e0 $a$ v\u00e0 $b$ $( a; b > 0)$ $(cm)$. <br\/> N\u1eeda chu vi c\u1ee7a h\u00ecnh b\u00ecnh h\u00e0nh l\u00e0: $2,8:2=1,4\\, (cm)$ <br\/> Do \u0111\u00f3 $a+b= 1,4\\, (cm)$ <br\/> T\u1ec9 s\u1ed1 \u0111\u1ed9 d\u00e0i hai c\u1ea1nh l\u00e0 $3 : 4$ n\u00ean: <br\/> $\\dfrac{a}{3}=\\dfrac{b}{4}$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u1ee7a d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau, ta \u0111\u01b0\u1ee3c: <br\/> $\\dfrac{a}{3}=\\dfrac{b}{4}$$=\\dfrac{a+b}{3+4}=\\dfrac{1,4}{7}=0,2$ <br\/> $\\Rightarrow \\left\\{ \\begin{align} & a=0,2.3=0,6\\, (cm) \\\\ & b=0,2.4=0,8\\, (cm) \\\\ \\end{align} \\right.$ <br\/> \u0110\u1ed9 d\u00e0i hai c\u1ea1nh k\u1ec1 c\u1ee7a h\u00ecnh b\u00ecnh h\u00e0nh l\u00e0 $0,6\\, cm$ v\u00e0 $0,8\\, cm$. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1523},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y <b> \u0110\u00fang<\/b> hay <b> Sai <\/b>","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho $\\Delta ABC$, t\u1eeb $M$ v\u00e0 $N$ l\u00e0 trung \u0111i\u1ec3m c\u1ee7a c\u00e1c c\u1ea1nh $AB, AC$ v\u1ebd $MH$ v\u00e0 $NK$ c\u00f9ng vu\u00f4ng g\u00f3c v\u1edbi $BC$. Khi \u0111\u00f3 ta ch\u1ec9 ra \u0111\u01b0\u1ee3c t\u1ee9 gi\u00e1c $MNKH$ l\u00e0 h\u00ecnh vu\u00f4ng. <\/span>","select":["\u0110\u00fang","Sai"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_2.jpg' \/><\/center> X\u00e9t $\\Delta ABC$ c\u00f3: $AM=BM; AN=CN$ n\u00ean $MN \/\/ BC$ <br\/> M\u00e0 $MH \\bot BC \\Rightarrow MH \\bot MN$ <br\/> $\\Rightarrow \\widehat{NMH}=90^o$ <br\/> X\u00e9t t\u1ee9 gi\u00e1c $MNKH$ c\u00f3: $\\widehat{NMH}=\\widehat{MHK}=\\widehat{NKH}=90^o$ <br\/> $\\Rightarrow MNKH$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft). <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai. <\/span><\/span> ","column":2}]}],"id_ques":1524},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y <b> \u0110\u00fang<\/b> hay <b> Sai <\/b>","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> C\u00e1c \u0111i\u1ec3m $A, B, C$ th\u1eb3ng h\u00e0ng theo th\u1ee9 t\u1ef1 \u0111\u00f3 v\u00e0 \u0111\u1ed1i x\u1ee9ng v\u1edbi c\u00e1c \u0111i\u1ec3m $A'; B'; C'$ qua \u0111\u01b0\u1eddng th\u1eb3ng $d$. Bi\u1ebft $BC=4\\, cm; AB=13\\, cm$ th\u00ec \u0111\u1ed9 d\u00e0i $A'C'$ l\u00e0 $17\\, cm$. <\/span>","select":["\u0110\u00fang","Sai"],"explain":" <span class='basic_left'> Do $A, B, C$ th\u1eb3ng h\u00e0ng theo th\u1ee9 t\u1ef1 \u0111\u00f3 n\u00ean: <br\/> $AB+BC=AC$ <br\/> $\\Rightarrow AC=13+4$ <br\/> $\\Rightarrow AC=17\\, (cm)$ <br\/> M\u00e0 c\u00e1c \u0111i\u1ec3m $A'; B'; C'$ l\u1ea7n l\u01b0\u1ee3t \u0111\u1ed1i x\u1ee9ng v\u1edbi c\u00e1c \u0111i\u1ec3m $A; B; C$ qua \u0111\u01b0\u1eddng th\u1eb3ng $d$ n\u00ean $A'; B'; C'$ c\u0169ng th\u1eb3ng h\u00e0ng theo th\u1ee9 t\u1ef1 \u0111\u00f3 <br\/> $\\Rightarrow A'C'=AC=17\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang. <\/span> <br\/> <b> L\u01b0u \u00fd: <\/b> <i> 1. Ba \u0111i\u1ec3m \u0111\u1ed1i x\u1ee9ng v\u1edbi ba \u0111i\u1ec3m kh\u00e1c th\u1eb3ng h\u00e0ng qua m\u1ed9t \u0111\u01b0\u1eddng th\u1eb3ng th\u00ec ba \u0111i\u1ec3m \u0111\u00f3 c\u0169ng th\u1eb3ng h\u00e0ng. <br\/> 2. Ba \u0111i\u1ec3m $A, B, C$ \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 th\u1eb3ng h\u00e0ng ($B$ n\u1eb1m gi\u1eefa $A$ v\u00e0 $C$) n\u1ebfu: $AB+BC=AC$ <br\/> 3. Hai \u0111i\u1ec3m $A', B'$ l\u1ea7n l\u01b0\u1ee3t \u0111\u1ed1i x\u1ee9ng v\u1edbi $A, B$ qua \u0111\u01b0\u1eddng th\u1eb3ng $d$ th\u00ec $AB=A'B'$. <\/i> <\/span> ","column":2}]}],"id_ques":1525},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["28"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho $\\Delta ABC$, trong \u0111\u00f3 $AB=11,5\\, cm; AC=2,5\\, cm$. V\u1ebd h\u00ecnh \u0111\u1ed1i x\u1ee9ng v\u1edbi tam gi\u00e1c \u0111\u00e3 cho qua trung \u0111i\u1ec3m c\u1ea1nh $BC$. Chu vi c\u1ee7a t\u1ee9 gi\u00e1c t\u1ea1o th\u00e0nh l\u00e0 _input_ $(cm)$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_3.jpg' \/><\/center> Qua trung \u0111i\u1ec3m c\u1ee7a c\u1ea1nh $BC$ th\u00ec: <br\/> $\\begin{align} & A\\to A' \\\\ & B\\to C \\\\ & C\\to B \\\\ \\end{align}$ <br\/> Do \u0111\u00f3 t\u1ee9 gi\u00e1c t\u1ea1o th\u00e0nh l\u00e0 $ABA'C$ <br\/> Ta c\u0169ng c\u00f3 \u0111\u01b0\u1ee3c: $A'C=AB; A'B=AC$ (t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng). <br\/> Chu vi c\u1ee7a t\u1ee9 gi\u00e1c $ABA'C$ l\u00e0: <br\/> $2(AB+AC)$$=2(11,5+2,5)=28\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $28$. <\/span> <\/span> "}]}],"id_ques":1526},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["2"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> H\u00ecnh vu\u00f4ng th\u1ee9 nh\u1ea5t c\u00f3 \u0111\u1ed9 d\u00e0i \u0111\u01b0\u1eddng ch\u00e9o l\u00e0 $4\\, m$, c\u1ea1nh c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 nh\u1ea5t l\u00e0 \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 hai. \u0110\u1ed9 d\u00e0i c\u1ea1nh c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 hai l\u00e0 _input_ $(m)$ <\/span> ","Hint":" T\u00ecm \u0111\u1ed9 d\u00e0i \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 hai r\u1ed3i t\u00ednh \u0111\u1ed9 d\u00e0i c\u1ea1nh c\u1ee7a n\u00f3.","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D2_3.jpg' \/><\/center> \u0110\u1ed9 d\u00e0i c\u1ea1nh c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 nh\u1ea5t l\u00e0: <br\/> $\\sqrt{4^2:2}$$=\\sqrt{8}=2\\sqrt{2}\\, (m)$ <br\/> Suy ra \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 hai l\u00e0: $2\\sqrt{2}\\, (m)$ <br\/> \u0110\u1ed9 d\u00e0i c\u1ea1nh c\u1ee7a h\u00ecnh vu\u00f4ng th\u1ee9 hai l\u00e0: <br\/> $\\sqrt{(2\\sqrt{2})^2:2}$$=\\sqrt{8:2}=\\sqrt{4}=2\\, (m)$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $2$. <\/span> <\/span> "}]}],"id_ques":1527},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho h\u00ecnh b\u00ecnh h\u00e0nh $ABCD$. G\u1ecdi $M, N$ l\u00e0 trung \u0111i\u1ec3m c\u1ee7a c\u00e1c c\u1ea1nh $AD, BC$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $BM, DN$ c\u1eaft \u0111\u01b0\u1eddng ch\u00e9o $AC$ l\u1ea7n l\u01b0\u1ee3t t\u1ea1i $P$ v\u00e0 $Q$. <br\/> Ta ch\u1ee9ng minh \u0111\u01b0\u1ee3c t\u1ee9 gi\u00e1c $MQNP$ l\u00e0 h\u00ecnh thoi. <\/span>","select":[" \u0110\u00fang"," Sai"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_4.jpg' \/><\/center> Ta th\u1ea5y $PQ$ v\u00e0 $MN$ l\u00e0 hai \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a t\u1ee9 gi\u00e1c $MQNP$. <br\/> $AC$ v\u00e0 $AB$ kh\u00f4ng vu\u00f4ng g\u00f3c n\u00ean $PQ$ v\u00e0 $MN$ c\u0169ng kh\u00f4ng vu\u00f4ng g\u00f3c. <br\/> Do \u0111\u00f3 t\u1ee9 gi\u00e1c $MQNP$ kh\u00f4ng l\u00e0 h\u00ecnh thoi. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai. <\/span><\/span> ","column":2}]}],"id_ques":1528},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho h\u00ecnh b\u00ecnh h\u00e0nh $ABCD$ c\u00f3 $\\widehat{A}=120^o$. \u0110\u01b0\u1eddng ph\u00e2n gi\u00e1c trong c\u1ee7a g\u00f3c $D$ \u0111i qua trung \u0111i\u1ec3m $E$ c\u1ee7a c\u1ea1nh $AB$. V\u1ebd $AH \\bot CD$, g\u1ecdi $M$ l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $CD$ <br\/> C\u00e2u n\u00e0o sau \u0111\u00e2y <b> sai<\/b>? <\/span>","select":[" A. $AB=2AD$"," B. $\\Delta ADC$ vu\u00f4ng c\u00e2n","C. $\\Delta ADM$ l\u00e0 tam gi\u00e1c \u0111\u1ec1u","D. $DE=2AH$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_5a.jpg' \/><\/center> Do $\\widehat{A}=120^o$ n\u00ean $\\widehat{D}=60^o$ <br\/> M\u00e0 $DE$ l\u00e0 ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $D$ n\u00ean $\\widehat{ADE}=30^0$ <br\/> Trong $\\Delta ADE$ c\u00f3: $\\widehat{A}=120^o; \\widehat{ADE}=30^o$ n\u00ean $\\widehat{AED}=30^o$ <br\/> Do \u0111\u00f3: $\\Delta ADE$ c\u00e2n t\u1ea1i $A$. <br\/> Suy ra: $AD=AE \\Rightarrow AB=2AE=2AD$. <br\/> <b> \u0110\u00e1p \u00e1n A \u0111\u00fang.<\/b> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_5d.jpg' \/><\/center> $\\Delta ADM$ c\u00f3 $AD=DM$ ($M$ l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $DC$). <br\/> M\u00e0 $\\widehat{D}=60^o$ n\u00ean $\\Delta ADM$ \u0111\u1ec1u. <br\/> <b> \u0110\u00e1p \u00e1n C \u0111\u00fang. <\/b> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_5c.jpg' \/><\/center> G\u1ecdi $K=AM\\cap DE$ <br\/> Do $\\Delta ADM$ \u0111\u1ec1u n\u00ean $DE$ l\u00e0 ph\u00e2n gi\u00e1c v\u00e0 c\u0169ng l\u00e0 \u0111\u01b0\u1eddng cao. <br\/> $\\Rightarrow DK=AH$ <br\/> M\u00e0 $DE=2DK$ ($ADME$ l\u00e0 h\u00ecnh thoi c\u00f3 hai \u0111\u01b0\u1eddng ch\u00e9o vu\u00f4ng g\u00f3c). <br\/> $\\Rightarrow DE=2AH$ <br\/> <b> \u0110\u00e1p \u00e1n D \u0111\u00fang.<\/b> <br\/> Do \u0111\u00f3 C\u00e2u B <b> sai.<\/b> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_5b.jpg' \/><\/center> <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1529},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho ba c\u00e2u","temp":"fill_the_blank","correct":[[["40"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}=70^o; \\widehat{B}=150^o$; $\\widehat{C}=60^o$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $AD$ v\u00e0 $BC$ c\u1eaft nhau t\u1ea1i $M$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $AB$ v\u00e0 $CD$ c\u1eaft nhau t\u1ea1i $N$. C\u00e1c tia ph\u00e2n gi\u00e1c c\u1ee7a c\u00e1c g\u00f3c $\\widehat{DMC}$ v\u00e0 $\\widehat{DNA}$ c\u1eaft nhau t\u1ea1i $I$. <br\/><br\/> <b> C\u00e2u 1: <\/b> T\u00ednh s\u1ed1 \u0111o g\u00f3c $\\widehat{AMB}$. <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{AMB}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_6.jpg' \/><\/center> Trong t\u1ee9 gi\u00e1c $ABCD$ c\u00f3: <br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}=360^o$ (\u0111\u1ecbnh l\u00ed t\u1ed5ng c\u00e1c g\u00f3c trong t\u1ee9 gi\u00e1c) <br\/> $\\Rightarrow \\widehat{D}=360^o-(\\widehat{A}+\\widehat{B}+\\widehat{C})$ <br\/> $=360^0-(70^o+150^o+60^o)$ <br\/> $=80^o$ <br\/>Ta c\u00f3: $\\widehat{MAB}+\\widehat{BAD}=180^o$ (hai g\u00f3c k\u1ec1 b\u00f9) <br\/> $\\Rightarrow \\widehat{MAB}=180^o-\\widehat{BAD} =180^o-70^o=110^o$ <br\/> M\u00e0 $\\widehat{ABC}=\\widehat{AMB}+\\widehat{MAB}$ (g\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh $B$ c\u1ee7a $\\Delta ABM$) <br\/> $\\widehat{AMB}=\\widehat{ABC}-\\widehat{MAB}$$=150^o-110^o=40^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $40$. <\/span> <\/span> "}]}],"id_ques":1530},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho ba c\u00e2u","temp":"fill_the_blank","correct":[[["30"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}=70^o; \\widehat{B}=150^o$; $\\widehat{C}=60^o$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $AD$ v\u00e0 $BC$ c\u1eaft nhau t\u1ea1i $M$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $AB$ v\u00e0 $CD$ c\u1eaft nhau t\u1ea1i $N$. C\u00e1c tia ph\u00e2n gi\u00e1c c\u1ee7a c\u00e1c g\u00f3c $\\widehat{DMC}$ v\u00e0 $\\widehat{DNA}$ c\u1eaft nhau t\u1ea1i $I$. <br\/><br\/> <b> C\u00e2u 2: <\/b> T\u00ednh s\u1ed1 \u0111o g\u00f3c $\\widehat{BNC}$. <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{BNC}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_6.jpg' \/><\/center> Ta c\u00f3: $\\widehat{NCB}+\\widehat{BCD}=180^o$ (hai g\u00f3c k\u1ec1 b\u00f9) <br\/> $\\Rightarrow \\widehat{NCB}=180^o-60^o=120^o$ <br\/> Ta c\u00f3: $\\widehat{NBC}+\\widehat{ABC}=180^o$ <br\/> $\\Rightarrow \\widehat{NBC}=180^o-\\widehat{ABC}$$=180^o-150^o=30^o$ <br\/> X\u00e9t $\\Delta BNC$ c\u00f3: <br\/> $\\widehat{NBC}+\\widehat{BNC}+\\widehat{BCN}=180^o$ <br\/> $\\Rightarrow \\widehat{BNC}=180^o-\\widehat{NBC}-\\widehat{BCN}$ <br\/> $=180^o-30^o-120^o=30^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $30$. <\/span> <\/span> "}]}],"id_ques":1531},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho ba c\u00e2u","temp":"fill_the_blank","correct":[[["115"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}=70^o; \\widehat{B}=150^o$; $\\widehat{C}=60^o$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $AD$ v\u00e0 $BC$ c\u1eaft nhau t\u1ea1i $M$. C\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng $AB$ v\u00e0 $CD$ c\u1eaft nhau t\u1ea1i $N$. C\u00e1c tia ph\u00e2n gi\u00e1c c\u1ee7a c\u00e1c g\u00f3c $\\widehat{DMC}$ v\u00e0 $\\widehat{DNA}$ c\u1eaft nhau t\u1ea1i $I$. <br\/><br\/> <b> C\u00e2u 3: <\/b> T\u00ednh s\u1ed1 \u0111o g\u00f3c $\\widehat{MIN}$. <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{MIN}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_6.jpg' \/><\/center> Theo c\u00e2u 1, ta t\u00ednh \u0111\u01b0\u1ee3c: $\\widehat{AMB}=40^o$ <br\/> M\u00e0 $MI$ l\u00e0 ph\u00e2n gi\u00e1c g\u00f3c $AMB$ n\u00ean: <br\/> $\\widehat{M_1}=\\widehat{M_2}=20^o$ <br\/> Theo c\u00e2u 2, ta t\u00ednh \u0111\u01b0\u1ee3c: $\\widehat{BNC}=30^o$ <br\/> M\u00e0 $NI$ l\u00e0 ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $BNC$ n\u00ean: <br\/> $\\widehat{N_1}=\\widehat{N_2}=15^o$ <br\/> X\u00e9t trong tam gi\u00e1c $MBN$: <br\/> $\\widehat{M_3}+\\widehat{N_3}=180^o-\\widehat{MBN}$$=180^o-150^o=30^o$ <br\/> X\u00e9t $\\Delta MIN$ c\u00f3: <br\/> $\\widehat{MIN}=180^o-(\\widehat{M_2}+\\widehat{M_3}+\\widehat{N_3}+\\widehat{N_2})$ <br\/> $=180^o-(20^o+30^o+15^o)$ <br\/> $=115^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $115$. <\/span> <\/span> "}]}],"id_ques":1532},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho b\u1ed1n c\u00e2u","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho $\\Delta ABC$ c\u00e2n t\u1ea1i $A$, \u0111\u01b0\u1eddng cao $AD$. G\u1ecdi $E$ l\u00e0 \u0111i\u1ec3m \u0111\u1ed1i x\u1ee9ng v\u1edbi $D$ qua trung \u0111i\u1ec3m $M$ c\u1ee7a $AC.$ <br\/><br\/> <b> C\u00e2u 1: <\/b> T\u1ee9 gi\u00e1c $ADCE$ l\u00e0 h\u00ecnh g\u00ec? <\/span>","select":[" A. H\u00ecnh b\u00ecnh h\u00e0nh"," B. H\u00ecnh ch\u1eef nh\u1eadt","C. H\u00ecnh thoi","D. H\u00ecnh vu\u00f4ng"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_7.jpg' \/><\/center> T\u1ee9 gi\u00e1c $ADCE$ c\u00f3: $AM = CM; DM = ME$ (gi\u1ea3 thi\u1ebft) <br\/> $\\Rightarrow ADCE$ l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <br\/> M\u1eb7t kh\u00e1c $\\widehat{ADC}={{90}^{0}}$ suy ra $ADCE$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1533},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho b\u1ed1n c\u00e2u","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho $\\Delta ABC$ c\u00e2n t\u1ea1i $A$, \u0111\u01b0\u1eddng cao $AD$. G\u1ecdi $E$ l\u00e0 \u0111i\u1ec3m \u0111\u1ed1i x\u1ee9ng v\u1edbi $D$ qua trung \u0111i\u1ec3m $M$ c\u1ee7a $AC.$ <br\/><br\/> <b> C\u00e2u 2: <\/b> T\u1ee9 gi\u00e1c $ABDM$ l\u00e0 h\u00ecnh g\u00ec? <\/span>","select":[" A. H\u00ecnh thang c\u00e2n"," B. H\u00ecnh thang","C. H\u00ecnh thoi","D. H\u00ecnh vu\u00f4ng"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_7.jpg' \/><\/center> Tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i $A$, $AD\\,\\bot \\,BC\\Rightarrow BD=CD$ <br\/>X\u00e9t $\u2206 ABC$ c\u00f3: $AM = CM; DC = BD$ <br\/> $\\Rightarrow DM$ l\u00e0 \u0111\u01b0\u1eddng trung b\u00ecnh c\u1ee7a $\\Delta ABC$ <br\/> $\\Rightarrow DM\/\/AB\\Rightarrow ABDM$ l\u00e0 h\u00ecnh thang (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1534},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho b\u1ed1n c\u00e2u","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho $\\Delta ABC$ c\u00e2n t\u1ea1i $A$, \u0111\u01b0\u1eddng cao $AD$. G\u1ecdi $E$ l\u00e0 \u0111i\u1ec3m \u0111\u1ed1i x\u1ee9ng v\u1edbi $D$ qua trung \u0111i\u1ec3m $M$ c\u1ee7a $AC.$ <br\/><br\/> <b> C\u00e2u 3: <\/b> $\\Delta ABC$ c\u1ea7n th\u00eam \u0111i\u1ec1u ki\u1ec7n g\u00ec \u0111\u1ec3 $ADCE$ l\u00e0 h\u00ecnh vu\u00f4ng? <\/span>","select":[" A. $AB=BC$"," B. $AB\\bot AC$","C. $\\widehat{B}=60^o$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_7.jpg' \/><\/center> \u0110\u1ec3 h\u00ecnh ch\u1eef nh\u1eadt $ADCE$ l\u00e0 h\u00ecnh vu\u00f4ng th\u00ec $AD = DC$<br\/> Khi \u0111\u00f3 $\u2206 ADC$ vu\u00f4ng c\u00e2n t\u1ea1i $D$. <br\/> $\\Rightarrow \\widehat{DAC}={{45}^{0}}$ <br\/> M\u00e0 $AD$ l\u00e0 \u0111\u01b0\u1eddng cao \u0111\u1ed3ng th\u1eddi l\u00e0 \u0111\u01b0\u1eddng ph\u00e2n gi\u00e1c. <br\/> $\\Rightarrow \\widehat{BAC}=90^o$ <br\/> V\u1eady \u0111\u1ec3 $ADCE$ l\u00e0 h\u00ecnh vu\u00f4ng th\u00ec tam gi\u00e1c $ABC$ vu\u00f4ng c\u00e2n t\u1ea1i $A$. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":3}]}],"id_ques":1535},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho b\u1ed1n c\u00e2u","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'>Cho $\\Delta ABC$ c\u00e2n t\u1ea1i $A$, \u0111\u01b0\u1eddng cao $AD$. G\u1ecdi $E$ l\u00e0 \u0111i\u1ec3m \u0111\u1ed1i x\u1ee9ng v\u1edbi $D$ qua trung \u0111i\u1ec3m $M$ c\u1ee7a $AC.$ <br\/><br\/> <b> C\u00e2u 4: <\/b> $\\Delta ABC$ c\u1ea7n th\u00eam \u0111i\u1ec1u ki\u1ec7n g\u00ec \u0111\u1ec3 $ABDM$ l\u00e0 h\u00ecnh thang c\u00e2n? <\/span>","select":[" A. $AB=BC$"," B. $\\widehat{A}=90^o$","C. $\\widehat{B}=80^o$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_7.jpg' \/><\/center> \u0110\u1ec3 h\u00ecnh thang $ABDM$ l\u00e0 h\u00ecnh thang c\u00e2n th\u00ec $\\widehat{ABD}=\\widehat{BAM}$<br\/> $\\Rightarrow \\Delta \\,\\,\\,ABC$ c\u00f3 $\\widehat{B}=\\widehat{A}$ <br\/> M\u00e0 $\\Delta ABC$ c\u00e2n t\u1ea1i $A$. <br\/> V\u1eady $\\Delta ABC$ l\u00e0 tam gi\u00e1c \u0111\u1ec1u. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A. <\/span><\/span> ","column":3}]}],"id_ques":1536},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho h\u00ecnh vu\u00f4ng $ABCD$ c\u1ea1nh $a, M$ l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $AB$. G\u1ecdi $N$ l\u00e0 giao \u0111i\u1ec3m c\u1ee7a $DM$ v\u00e0 $BC$. <br\/><br\/> <b> C\u00e2u 1: <\/b> T\u1ee9 gi\u00e1c $ANBD$ l\u00e0 h\u00ecnh g\u00ec?<\/span>","select":["A. H\u00ecnh thang","B. H\u00ecnh b\u00ecnh h\u00e0nh","C. H\u00ecnh ch\u1eef nh\u1eadt","D. H\u00ecnh thoi"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_8.jpg' \/><\/center> X\u00e9t $\\Delta AMD$ v\u00e0 $\\Delta BMN$ c\u00f3: <br\/> + $\\widehat{MAD}=\\widehat{MBN}={{90}^{0}}$ <br\/> + $AM = BM$ (gi\u1ea3 thi\u1ebft) <br\/> + ${{\\widehat{M}}_{1}}={{\\widehat{M}}_{2}}$ (hai g\u00f3c \u0111\u1ed1i \u0111\u1ec9nh) <br\/> $\\Rightarrow \\Delta \\,AMD=\\Delta \\,BMN\\,\\,\\left( g-c-g \\right)\\Rightarrow AD=BN$ <br\/> T\u1ee9 gi\u00e1c $ANBD$ c\u00f3: $AD = BN; AD \/\/ BN$ n\u00ean l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft). <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1537},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho h\u00ecnh vu\u00f4ng $ABCD$ c\u1ea1nh $a, M$ l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $AB$. G\u1ecdi $N$ l\u00e0 giao \u0111i\u1ec3m c\u1ee7a $DM$ v\u00e0 $BC$. <br\/><br\/> <b> C\u00e2u 2: <\/b> K\u1ebb $Cx \/\/ DN$, $Cx$ c\u1eaft $AB$ t\u1ea1i $P$. T\u1ee9 gi\u00e1c $MNPC$ l\u00e0 h\u00ecnh g\u00ec? <\/span>","select":[" A. H\u00ecnh b\u00ecnh h\u00e0nh"," B. H\u00ecnh ch\u1eef nh\u1eadt","C. H\u00ecnh thoi","D. H\u00ecnh vu\u00f4ng"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai9/lv1/img\/H819_D1_8.jpg' \/><\/center> X\u00e9t $\\Delta MBN$ v\u00e0 $\\Delta PBC$ c\u00f3: <br\/> + $\\widehat{MBN}=\\widehat{PBC}={{90}^{0}}$<br\/> + $BN = BC$ (c\u00f9ng b\u1eb1ng $AD$) <br\/> + ${{\\widehat{N}}_{1}}={{\\widehat{C}}_{1}}$ ( so le trong) <br\/> $\\Rightarrow \\Delta \\,MBN=\\Delta \\,PBC\\,\\,\\left( g-c-g \\right)\\Rightarrow MN=PC$ <br\/> T\u1ee9 gi\u00e1c $MNPC$ c\u00f3: $MN = PC; MN \/\/ PC$ (gi\u1ea3 thi\u1ebft) n\u00ean $MNPC$ l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft). <br\/> H\u01a1n n\u1eefa: $CN\\,\\bot \\,MP\\,\\,\\left( do\\,\\,BC\\bot MB \\right)$ <br\/> $\\Rightarrow MNPC$ l\u00e0 h\u00ecnh thoi (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft). <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":1538},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["80"],["70"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD $ c\u00f3 $\\widehat{A}=80^o; \\widehat{B}=130^o$; $\\widehat{C}-\\widehat{D}=10^o$. T\u00ednh s\u1ed1 \u0111o $\\widehat{C}$ v\u00e0 $\\widehat{D}$. <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> <br\/> $\\widehat{C}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <br\/>$\\widehat{D}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span> ","Hint":"T\u00ecm t\u1ed5ng s\u1ed1 \u0111o hai g\u00f3c $C$ v\u00e0 $D$. <br\/> T\u00ecm s\u1ed1 \u0111o hai g\u00f3c $C$ v\u00e0 $D$ khi bi\u1ebft t\u1ed5ng v\u00e0 hi\u1ec7u.","explain":" <span class='basic_left'> Trong t\u1ee9 gi\u00e1c $ABCD$ c\u00f3: <br\/> $\\widehat{C}+\\widehat{D}=360^o-(\\widehat{A}+\\widehat{B})$ <br\/> $=360^o-(80^o+130^o)$ <br\/> $=150^o$ <br\/> M\u00e0 $\\widehat{C}-\\widehat{D}=10^o$ <br\/> $\\widehat{C}= \\dfrac{150^o+10^o}{2}=80^o$ <br\/> $\\widehat{D}=\\dfrac{150^o-10^o}{2}=70^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $80$ v\u00e0 $70$. <\/span> <\/span> "}]}],"id_ques":1539},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["120"],["60"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh b\u00ecnh h\u00e0nh $ABCD$ c\u00f3 $\\widehat{A}=2\\widehat{B}$. T\u00ednh s\u1ed1 \u0111o $\\widehat{C}$ v\u00e0 $\\widehat{D}$. <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> <br\/> $\\widehat{C}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <br\/>$\\widehat{D}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span> ","Hint":"T\u00ecm t\u1ed5ng s\u1ed1 \u0111o hai g\u00f3c $A$ v\u00e0 $B$ <br\/> T\u00ecm s\u1ed1 \u0111o hai g\u00f3c $A$ v\u00e0 $B$ r\u1ed3i suy ra s\u1ed1 \u0111o hai g\u00f3c $C$ v\u00e0 $D$.","explain":" <span class='basic_left'> Trong h\u00ecnh b\u00ecnh h\u00e0nh $ABCD$ c\u00f3: <br\/> $\\widehat{A}+\\widehat{B}=180^o$ <br\/> M\u00e0 $\\widehat{A}=2\\widehat{B}$ <br\/> $\\Rightarrow 3\\widehat{B}= 180^o$ <br\/> $ \\Rightarrow \\widehat{B}={180^o}:{3}=60^o$ <br\/> $\\Rightarrow \\widehat{A}=2\\widehat{B}=120^o$ <br\/> Theo t\u00ednh ch\u1ea5t h\u00ecnh b\u00ecnh h\u00e0nh: <br\/> $\\widehat{C}=\\widehat{A}=120^o$ <br\/> $\\widehat{D}=\\widehat{B}=60^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $120$ v\u00e0 $60$. <\/span> <\/span> "}]}],"id_ques":1540}],"lesson":{"save":0,"level":1}}