{"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'> H\u00ecnh ch\u1eef nh\u1eadt l\u00e0: <\/span>","select":["A. T\u1ee9 gi\u00e1c c\u00f3 m\u1ed9t g\u00f3c vu\u00f4ng","B. T\u1ee9 gi\u00e1c c\u00f3 hai g\u00f3c vu\u00f4ng","C. T\u1ee9 gi\u00e1c c\u00f3 ba g\u00f3c vu\u00f4ng","D. C\u1ea3 ba c\u00e2u tr\u00ean \u0111\u1ec1u sai"],"explain":" <span class='basic_left'> H\u00ecnh ch\u1eef nh\u1eadt l\u00e0 t\u1ee9 gi\u00e1c c\u00f3 ba g\u00f3c vu\u00f4ng. <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_1.jpg' \/><\/center> <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":1431},{"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'> H\u00ecnh b\u00ecnh h\u00e0nh $ABCD$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt khi: <\/span>","select":["A. $AB=BC$","B. $AC=BD$","C. $BC=CD$","D. $AC\\bot BD$"],"explain":" <span class='basic_left'> Theo d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft, h\u00ecnh b\u00ecnh h\u00e0nh c\u00f3 hai \u0111\u01b0\u1eddng ch\u00e9o b\u1eb1ng nhau l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. T\u1ee9c l\u00e0: h\u00ecnh b\u00ecnh h\u00e0nh $ABCD$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt khi: $AC=BD$ <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_2.jpg' \/><\/center> <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":1432},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho h\u00ecnh ch\u1eef nh\u1eadt c\u00f3 c\u00e1c k\u00edch th\u01b0\u1edbc l\u00e0 $6\\, cm$ v\u00e0 $8\\, cm$. Khi \u0111\u00f3 \u0111\u1ed9 d\u00e0i \u0111\u01b0\u1eddng ch\u00e9o h\u00ecnh ch\u1eef nh\u1eadt l\u00e0: <\/span>","select":["A. $10\\, cm$","B. $9\\, cm$","C. $12\\, cm$","D. $14\\, cm$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_3.jpg' \/><\/center> X\u00e9t h\u00ecnh ch\u1eef nh\u1eadt $ABCD$ c\u00f3: $AB=8\\, cm; BC=6\\, cm$ <br\/> Tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $B$ (t\u00ednh ch\u1ea5t h\u00ecnh ch\u1eef nh\u1eadt) <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00fd Pi - ta - go v\u00e0o tam gi\u00e1c $ABC$ \u0111\u01b0\u1ee3c: <br\/> $AB^2+BC^2=AC^2$ <br\/> $\\Rightarrow AC^2=8^2+6^2=100$ <br\/> $\\Rightarrow AC=10\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":1433},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["9"]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh v\u1ebd sau: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_4.jpg' \/><\/center> Bi\u1ebft $ABCD$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <br\/> T\u00ednh \u0111\u1ed9 d\u00e0i c\u1ea1nh $BC$. <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $BC=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\, (cm)$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_4.jpg' \/><\/center> H\u00ecnh ch\u1eef nh\u1eadt $ABCD$ c\u00f3: $AB=12\\, cm; AC=15\\, cm$ <br\/> Tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $B$. (t\u00ednh ch\u1ea5t h\u00ecnh ch\u1eef nh\u1eadt) <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00fd Pi - ta - go v\u00e0o tam gi\u00e1c $ABC$ \u0111\u01b0\u1ee3c: <br\/> $AB^2+BC^2=AC^2$ <br\/> $\\Rightarrow BC^2=AC^2-AB^2$ <br\/> $\\Rightarrow BC^2=15^2-12^2=81$ <br\/> $\\Rightarrow BC=9\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $9$. <\/span> <\/span> "}]}],"id_ques":1434},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["11"]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh v\u1ebd sau: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_5.jpg' \/><\/center> Bi\u1ebft $ABCD$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <br\/> T\u00ednh \u0111\u1ed9 d\u00e0i \u0111\u01b0\u1eddng ch\u00e9o $BD$. <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $BD=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\, cm$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_5.jpg' \/><\/center> H\u00ecnh ch\u1eef nh\u1eadt $ABCD$ c\u00f3: $AB=6\\sqrt{2} \\, cm; AD=7\\, cm$ <br\/> Tam gi\u00e1c $ABD$ vu\u00f4ng t\u1ea1i $A$ (t\u00ednh ch\u1ea5t h\u00ecnh ch\u1eef nh\u1eadt) <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00fd Pi - ta - go v\u00e0o tam gi\u00e1c $ABD$ \u0111\u01b0\u1ee3c: <br\/> $AB^2+AD^2=BD^2$ <br\/> $\\Rightarrow BD^2=(6\\sqrt{2})^2+7^2$ <br\/> $\\Rightarrow BD^2=121$ <br\/> $\\Rightarrow BD=11\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $11$. <\/span> <\/span> "}]}],"id_ques":1435},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["14"]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh v\u1ebd sau: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_6.jpg' \/><\/center>Bi\u1ebft $ABCD$ l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <br\/> T\u00ednh chu vi c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt $ABCD$. <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\, (cm)$ <\/span> ","hint":" Chu vi c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt b\u1eb1ng hai l\u1ea7n t\u1ed5ng hai k\u00edch th\u01b0\u1edbc c\u1ee7a n\u00f3.","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_6.jpg' \/><\/center> H\u00ecnh ch\u1eef nh\u1eadt $ABCD$ c\u00f3: $BD=5 \\, cm; BC=4\\, cm$ <br\/> Tam gi\u00e1c $BDC$ vu\u00f4ng t\u1ea1i $C$ (t\u00ednh ch\u1ea5t h\u00ecnh ch\u1eef nh\u1eadt) <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00fd Pi - ta - go v\u00e0o tam gi\u00e1c $BDC$ \u0111\u01b0\u1ee3c: <br\/> $BC^2+DC^2=BD^2$ <br\/> $\\Rightarrow DC^2=BD^2-BC^2=5^2-4^2$ <br\/> $\\Rightarrow DC^2=9$ <br\/> $\\Rightarrow DC=3\\, (cm)$ <br\/> Chu vi c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt $ABCD$ l\u00e0: <br\/> $2(4+3)=14\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $14$. <\/span> <\/span> "}]}],"id_ques":1436},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t <br\/> Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> H\u00ecnh thang c\u00f3 hai g\u00f3c \u1edf \u0111\u00e1y b\u1eb1ng nhau v\u00e0 trong c\u00e1c g\u00f3c c\u00f3 m\u1ed9t g\u00f3c vu\u00f4ng l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <\/span>","select":[" \u0110\u00fang"," Sai"],"explain":" <span class='basic_left'> H\u00ecnh thang c\u00f3 hai g\u00f3c \u1edf \u0111\u00e1y b\u1eb1ng nhau l\u00e0 h\u00ecnh thang c\u00e2n <br\/> M\u00e0 h\u00ecnh thang c\u00e2n c\u00f3 m\u1ed9t trong c\u00e1c g\u00f3c l\u00e0 g\u00f3c vu\u00f4ng th\u00ec n\u00f3 l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang. <\/span><\/span> ","column":2}]}],"id_ques":1437},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t <br\/> 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'> H\u00ecnh thang vu\u00f4ng c\u0169ng l\u00e0 m\u1ed9t h\u00ecnh ch\u1eef nh\u1eadt. <\/span>","select":[" \u0110\u00fang"," Sai"],"explain":" <span class='basic_left'> Kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 sai. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai. <\/span><\/span> ","column":2}]}],"id_ques":1438},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t <br\/> 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'> H\u00ecnh b\u00ecnh h\u00e0nh c\u00f3 hai c\u1ea1nh k\u1ec1 b\u1eb1ng nhau l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt.<\/span>","select":[" \u0110\u00fang"," Sai"],"explain":" <span class='basic_left'> H\u00ecnh b\u00ecnh h\u00e0nh c\u00f3 m\u1ed9t g\u00f3c vu\u00f4ng l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai. <\/span><\/span> ","column":2}]}],"id_ques":1439},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> H\u00ecnh ch\u1eef nh\u1eadt c\u00f3 bao nhi\u00eau t\u00e2m \u0111\u1ed1i x\u1ee9ng? <\/span>","select":["A. 1","B. 2","C. 3","D. 4"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_2.jpg' \/><\/center> H\u00ecnh ch\u1eef nh\u1eadt c\u00f3 m\u1ed9t t\u00e2m \u0111\u1ed1i x\u1ee9ng l\u00e0 giao c\u1ee7a hai \u0111\u01b0\u1eddng ch\u00e9o. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A. <\/span><\/span> ","column":4}]}],"id_ques":1440},{"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 h\u00ecnh b\u00ecnh h\u00e0nh $ABCD$. Ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $A$ c\u1eaft ph\u00e2n gi\u00e1c c\u00e1c g\u00f3c $B$ v\u00e0 $D$ l\u1ea7n l\u01b0\u1ee3t t\u1ea1i $H$ v\u00e0 $G$, ph\u00e2n gi\u00e1c g\u00f3c $C$ c\u1eaft ph\u00e2n gi\u00e1c g\u00f3c $D$ v\u00e0 $B$ l\u1ea7n l\u01b0\u1ee3t t\u1ea1i $E$ v\u00e0 $F$. <br\/> T\u1ee9 gi\u00e1c $EFGH$ l\u00e0 h\u00ecnh g\u00ec?<\/span>","select":["A. H\u00ecnh thang c\u00e2n","B. H\u00ecnh b\u00ecnh h\u00e0nh","C. H\u00ecnh ch\u1eef nh\u1eadt"],"hint":"X\u00e9t tam gi\u00e1c $DEC$ v\u00e0 t\u00ednh g\u00f3c $E$. ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_7.jpg' \/><\/center> Ta c\u00f3: <br\/> $\\widehat{{{D}_{1}}}=\\widehat{{{D}_{2}}};\\,\\,\\widehat{{{C}_{1}}}=\\widehat{{{C}_{2}}}$ (gi\u1ea3 thi\u1ebft) <br\/> M\u00e0 $AD\/\/ BC$ (t\u00ednh ch\u1ea5t) <br\/> $\\Rightarrow \\widehat{D}+\\widehat{C}={{180}^{o}}$ (trong c\u00f9ng ph\u00eda b\u00f9 nhau)<br\/> $\\Rightarrow 2\\left( \\widehat{{{D}_{1}}}+\\widehat{{{C}_{1}}} \\right)={{180}^{o}}\\Rightarrow \\widehat{{{D}_{1}}}+\\widehat{{{C}_{1}}}={{90}^{o}}$<br\/> X\u00e9t $\\Delta DEC:\\,\\,\\widehat{{{D}_{1}}}+\\widehat{{{C}_{1}}}+\\widehat{E_{1}}={{180}^{o}}\\Rightarrow \\widehat{E_{1}}={{90}^{o}}$<br\/> T\u01b0\u01a1ng t\u1ef1 ta ch\u1ee9ng minh \u0111\u01b0\u1ee3c $\\widehat{H_{1}}={{90}^{o}};\\widehat{G_{1}}={{90}^{o}}$ <br\/> X\u00e9t t\u1ee9 gi\u00e1c $EFGH$ ta c\u00f3: $\\widehat{E_{1}}=\\widehat{H_{1}}=\\widehat{G_{1}}={{90}^{o}}$<br\/>$\\Rightarrow $ T\u1ee9 gi\u00e1c $EFGH$ 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 C. <\/span><\/span> ","column":3}]}],"id_ques":1441},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t <br\/> Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> Trong tam gi\u00e1c vu\u00f4ng, \u0111\u01b0\u1eddng trung tuy\u1ebfn \u1ee9ng v\u1edbi c\u1ea1nh huy\u1ec1n b\u1eb1ng m\u1ed9t n\u1eeda c\u1ea1nh huy\u1ec1n. <\/span>","select":[" \u0110\u00fang"," Sai"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_8.jpg' \/><\/center> Kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 <b> \u0111\u00fang<\/b>. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang. <\/span><\/span> ","column":2}]}],"id_ques":1442},{"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":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_9.jpg' \/><\/center> Cho h\u00ecnh v\u1ebd nh\u01b0 tr\u00ean. <br\/> <b> C\u00e2u 1:<\/b> $\\Delta ABF$ v\u00e0 $\\Delta ACF$ l\u00e0 c\u00e1c tam gi\u00e1c g\u00ec? <\/span>","select":["A. Tam gi\u00e1c c\u00e2n","B. Tam gi\u00e1c vu\u00f4ng","C. Tam gi\u00e1c \u0111\u1ec1u"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_9.jpg' \/><\/center> Do $\\Delta ABC$ vu\u00f4ng t\u1ea1i $A$ v\u00e0 $AF$ l\u00e0 \u0111\u01b0\u1eddng trung tuy\u1ebfn \u1ee9ng v\u1edbi c\u1ea1nh \u0111\u00e1y $BC$. <br\/> $\\Rightarrow AF=BF=CF$ <br\/> Do \u0111\u00f3 c\u00e1c tam gi\u00e1c $ABF$ v\u00e0 $ACF$ l\u00e0 c\u00e1c tam gi\u00e1c c\u00e2n. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A. <\/span><\/span> ","column":3}]}],"id_ques":1443},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["14"]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_9.jpg' \/><\/center> Cho h\u00ecnh v\u1ebd nh\u01b0 tr\u00ean. <br\/> <b> C\u00e2u 2:<\/b> Cho $AF=7\\, cm$ th\u00ec \u0111\u1ed9 d\u00e0i c\u1ea1nh $BC$ l\u00e0 $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$ $(cm)$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_9.jpg' \/><\/center> Theo c\u00e2u 1, ta \u0111\u00e3 ch\u1ec9 ra: $AF=BF=CF$ <br\/> T\u1ee9c l\u00e0: $BC=2AF=2.7=14\\, (cm)$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $14$. <\/span> <\/span> "}]}],"id_ques":1444},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["="]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_10.jpg' \/><\/center> Cho h\u00ecnh v\u1ebd nh\u01b0 tr\u00ean. <br\/> Bi\u1ebft $\\widehat{A}=90^o$; $BM=CM$ <br\/> <b> C\u00e2u 1:<\/b> So s\u00e1nh hai g\u00f3c $\\widehat{BAH}$ v\u00e0 $\\widehat{MCA}$. <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{BAH}\\, \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\,\\widehat{MCA}$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_10.jpg' \/><\/center> Do $\\Delta ABC$ vu\u00f4ng t\u1ea1i $A$ n\u00ean: <br\/> $\\widehat{MCA}=90^o-\\widehat{B}$ <br\/> $\\Delta ABH$ vu\u00f4ng t\u1ea1i $H$ n\u00ean: <br\/> $\\widehat{BAH}=90^o-\\widehat{B}$ <br\/> Do \u0111\u00f3: $\\widehat{BAH}=\\widehat{MCA}$. <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 d\u1ea5u $=$. <\/span> <\/span> "}]}],"id_ques":1445},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["="]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_10.jpg' \/><\/center> Cho h\u00ecnh v\u1ebd nh\u01b0 tr\u00ean. <br\/> Bi\u1ebft $\\widehat{A}=90^o$; $BM=CM$ <br\/> <b> C\u00e2u 2:<\/b> So s\u00e1nh hai g\u00f3c $\\widehat{CAH}$ v\u00e0 $\\widehat{MBA}$ <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{CAH}\\, \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\,\\widehat{MBA}$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_10.jpg' \/><\/center> Do $\\Delta ABC$ vu\u00f4ng t\u1ea1i $A$ n\u00ean: <br\/> $\\widehat{MBA}=90^o-\\widehat{C}$ <br\/> $\\Delta ACH$ vu\u00f4ng t\u1ea1i $H$ n\u00ean: <br\/> $\\widehat{CAH}=90^o-\\widehat{C}$ <br\/> Do \u0111\u00f3: $\\widehat{MBA}=\\widehat{CAH}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 d\u1ea5u $=$. <\/span> <\/span> "}]}],"id_ques":1446},{"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 \u1edf $A$ c\u00f3 $M$ v\u00e0 $N$ l\u1ea7n l\u01b0\u1ee3t l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $BC$ v\u00e0 $AC$. \u0110\u01b0\u1eddng th\u1eb3ng $MN$ c\u1eaft \u0111\u01b0\u1eddng th\u1eb3ng song song v\u1edbi $BC$ k\u1ebb t\u1eeb $A$ t\u1ea1i \u0111i\u1ec3m $D$. <br\/> <b> C\u00e2u 1:<\/b> $\\Delta AND$ l\u00e0 tam gi\u00e1c c\u00e2n <b> \u0111\u00fang<\/b> hay <b>sai <\/b>?<\/span>","select":[" \u0110\u00fang"," Sai"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_11ab.jpg' \/><\/center> X\u00e9t $\\Delta ABC$ c\u00f3: $AN=CN; BM=CM$ <br\/> $\\Rightarrow MN$ l\u00e0 \u0111\u01b0\u1eddng trung b\u00ecnh c\u1ee7a $\\Delta ABC$. <br\/> $\\Rightarrow MN \/\/ AB$ n\u00ean $\\widehat{M_1}=\\widehat{B}$ (\u0111\u1ed3ng v\u1ecb) <br\/>M\u00e0 $\\widehat{B}=\\widehat{C}$ ($\\Delta ABC$ c\u00e2n t\u1ea1i $A$) <br\/> $\\Rightarrow \\widehat{M_1}=\\widehat{C}$ (1) <br\/> Do $AD \/\/ BC$ n\u00ean $\\widehat{ADN}=\\widehat{M_1}; \\widehat{DAN}=\\widehat{C}$ (so le trong) (2) <br\/> T\u1eeb (1) v\u00e0 (2) $\\Rightarrow \\widehat{ADN}=\\widehat{DAN}$ <br\/> $\\Rightarrow \\Delta AND$ c\u00e2n t\u1ea1i $N$. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang. <\/span><\/span> ","column":2}]}],"id_ques":1447},{"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":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'>Cho $\\Delta ABC$ c\u00e2n \u1edf $A$ c\u00f3 $M$ v\u00e0 $N$ l\u1ea7n l\u01b0\u1ee3t l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $BC$ v\u00e0 $AC$. \u0110\u01b0\u1eddng th\u1eb3ng $MN$ c\u1eaft \u0111\u01b0\u1eddng th\u1eb3ng song song v\u1edbi $BC$ k\u1ebb t\u1eeb $A$ t\u1ea1i \u0111i\u1ec3m $D$. <br\/> <b> C\u00e2u 2:<\/b> T\u1ee9 gi\u00e1c $ABMD$ l\u00e0 h\u00ecnh g\u00ec?<\/span>","select":["A. H\u00ecnh ch\u1eef nh\u1eadt","B. H\u00ecnh thang","C. H\u00ecnh b\u00ecnh h\u00e0nh"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_11ab.jpg' \/><\/center> Theo c\u00e2u 1, ta ch\u1ec9 ra \u0111\u01b0\u1ee3c: $MD\/\/AB$ v\u00e0 $AD\/\/BM$ <br\/> Do \u0111\u00f3 t\u1ee9 gi\u00e1c $ABMD$ 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 C. <\/span><\/span> ","column":3}]}],"id_ques":1448},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho b\u1ed1n c\u00e2u","temp":"fill_the_blank","correct":[[["="]]],"list":[{"point":5,"width":20,"type_input":"","ques":"<span class='basic_left'> Cho $\\Delta ABC$ c\u00e2n \u1edf $A$ c\u00f3 $M$ v\u00e0 $N$ l\u1ea7n l\u01b0\u1ee3t l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $BC$ v\u00e0 $AC$. \u0110\u01b0\u1eddng th\u1eb3ng $MN$ c\u1eaft \u0111\u01b0\u1eddng th\u1eb3ng song song v\u1edbi $BC$ k\u1ebb t\u1eeb $A$ t\u1ea1i \u0111i\u1ec3m $D$. <br\/> <b> C\u00e2u 3:<\/b> So s\u00e1nh $MD$ v\u1edbi $AC$ <br\/><br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $MD\\, \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\,AC$ <\/span> ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_11ab.jpg' \/><\/center> Theo c\u00e2u 2, ta ch\u1ee9ng minh \u0111\u01b0\u1ee3c $ABMD$ l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh. <br\/> $\\Rightarrow AB=MD$ <br\/> M\u00e0 $AB=AC$ (gi\u1ea3 thi\u1ebft) n\u00ean $MD=AC$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 d\u1ea5u $=$. <\/span> <\/span> "}]}],"id_ques":1449},{"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 \u1edf $A$ c\u00f3 $M$ v\u00e0 $N$ l\u1ea7n l\u01b0\u1ee3t l\u00e0 trung \u0111i\u1ec3m c\u1ee7a $BC$ v\u00e0 $AC$. \u0110\u01b0\u1eddng th\u1eb3ng $MN$ c\u1eaft \u0111\u01b0\u1eddng th\u1eb3ng song song v\u1edbi $BC$ k\u1ebb t\u1eeb $A$ t\u1ea1i \u0111i\u1ec3m $D$. <br\/> <b> C\u00e2u 4:<\/b> T\u1ee9 gi\u00e1c $ADCM$ l\u00e0 h\u00ecnh g\u00ec?<\/span>","select":["A. H\u00ecnh ch\u1eef nh\u1eadt","B. H\u00ecnh thang","C. H\u00ecnh b\u00ecnh h\u00e0nh"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai6/lv1/img\/H816_D1_11d.jpg' \/><\/center> Theo c\u00e2u 3, ta ch\u1ee9ng minh \u0111\u01b0\u1ee3c: $AD \/\/ BM; AD = BM$ ($ABMD$ l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh) <br\/> M\u00e0 $BM=MC, M \\in BC$<br\/>$ \\Rightarrow AD = MC; AD \/\/ MC$ <br\/> Do \u0111\u00f3 $ADCM$ l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh (d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft) (1) <br\/> Tam gi\u00e1c $ABC$ c\u00e2n \u1edf $A$ v\u00e0 $AM$ l\u00e0 trung tuy\u1ebfn n\u00ean $AM$ c\u0169ng l\u00e0 \u0111\u01b0\u1eddng cao. <br\/> $\\Rightarrow AM \\bot BC$ hay $\\widehat{AMC}=90^o$ (2)<br\/> T\u1eeb (1) v\u00e0 (2) t\u1ee9 gi\u00e1c $ADCM$ 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 A. <\/span><\/span>","column":3}]}],"id_ques":1450}],"lesson":{"save":0,"level":1}}