{"segment":[{"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":"Tam gi\u00e1c c\u00e2n l\u00e0 tam gi\u00e1c c\u00f3 hai c\u1ea1nh b\u1eb1ng nhau: ","select":["\u0110\u00fang","Sai"],"explain":"\u0110\u00fang theo \u0111\u1ecbnh ngh\u0129a tam gi\u00e1c c\u00e2n. ","column":2}]}],"id_ques":1671},{"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":"Tam gi\u00e1c c\u00e2n c\u00f3 m\u1ed9t g\u00f3c b\u1eb1ng $60^o$ th\u00ec l\u00e0 tam gi\u00e1c \u0111\u1ec1u","select":["\u0110\u00fang","Sai"],"explain":" <b> \u0110\u00e1p \u00e1n ch\u1ecdn l\u00e0 \u0110\u00fang<\/b>","column":2}]}],"id_ques":1672},{"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":"T\u00ecm c\u00e2u ph\u00e1t bi\u1ec3u sai: ","select":["A. Tam gi\u00e1c c\u00f3 hai \u0111\u1ec9nh b\u1eb1ng nhau l\u00e0 tam gi\u00e1c c\u00e2n. ","B. Tam gi\u00e1c c\u00f3 hai g\u00f3c b\u1eb1ng nhau l\u00e0 tam gi\u00e1c c\u00e2n.","C. Tam gi\u00e1c c\u00f3 hai c\u1ea1nh b\u1eb1ng nhau l\u00e0 tam gi\u00e1c c\u00e2n.","D. Tam gi\u00e1c c\u00f3 ba c\u1ea1nh b\u1eb1ng nhau l\u00e0 tam gi\u00e1c \u0111\u1ec1u. "],"explain":"<b>Ph\u00e1t bi\u1ec3u sai l\u00e0 A.<\/b> <br\/> V\u00ec tam gi\u00e1c c\u00f3 hai c\u1ea1nh b\u1eb1ng nhau ho\u1eb7c hai g\u00f3c b\u1eb1ng nhau l\u00e0 tam gi\u00e1c c\u00e2n. ","column":1}]}],"id_ques":1673},{"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":"Tam gi\u00e1c vu\u00f4ng c\u00e2n l\u00e0 tam gi\u00e1c vu\u00f4ng c\u00f3: ","select":["A. Hai c\u1ea1nh g\u00f3c vu\u00f4ng b\u1eb1ng nhau.","B. C\u00f3 m\u1ed9t g\u00f3c nh\u1ecdn b\u1eb1ng $60^{o} $. ","C. C\u1ea1nh huy\u1ec1n b\u1eb1ng c\u1ea1nh g\u00f3c vu\u00f4ng. ","D. C\u00f3 m\u1ed9t g\u00f3c nh\u1ecdn b\u1eb1ng $30^{o} $. "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-03.png' \/><\/center> Tam gi\u00e1c vu\u00f4ng c\u00e2n l\u00e0 tam gi\u00e1c vu\u00f4ng c\u00f3: <br\/> hai c\u1ea1nh g\u00f3c vu\u00f4ng b\u1eb1ng nhau. (theo \u0111\u1ecbnh ngh\u0129a) <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span> ","column":2}]}],"id_ques":1674},{"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":"M\u1ed7i g\u00f3c c\u1ee7a tam gi\u00e1c \u0111\u1ec1u c\u00f3 s\u1ed1 \u0111o l\u00e0: ","select":["A. $60^{o} $ ","B. $45^{o} $ ","C. $30^{o} $ ","D. $90^{o} $ "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-04.png' \/><\/center> <span class='basic_left'>Tam gi\u00e1c $ABC$ \u0111\u1ec1u n\u00ean $AB = AC = BC$ <br\/> Do $AB = AC$ n\u00ean $\\triangle ABC $ c\u00e2n t\u1ea1i A $\\Rightarrow \\widehat{B} = \\widehat{C} $ <br\/> Do $AB = BC$ n\u00ean $\\triangle ABC $ c\u00e2n t\u1ea1i B <br\/> $\\Rightarrow \\widehat{A} = \\widehat{C} $ <br\/> Suy ra $ \\widehat{A} = \\widehat{B} = \\widehat{C} = \\dfrac{180^{o}}{3} = 60^{o} $ <br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span>","column":2}]}],"id_ques":1675},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Cho h\u00ecnh v\u1ebd: <br\/> T\u00ecm c\u00e2u tr\u1ea3 l\u1eddi sai. <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-06.png' \/><\/center> ","select":["A. Tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A. ","B. $AB = AC $ ","C. $\\widehat{B} = \\widehat{C} $ ","D. $\\widehat{A} = \\widehat{B} $ "],"explain":"<b> C\u00e2u sai l\u00e0 D.<\/b> <br\/> V\u00ec c\u00f3 $AB = AC$ n\u00ean tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A <br\/> $\\Rightarrow \\widehat{B} = \\widehat{C} $","column":2}]}],"id_ques":1676},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n SAI","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" Cho h\u00ecnh v\u1ebd, bi\u1ebft $\\widehat{A} = 40^{o}, Ax \/\/ By, AB = AC $.<br\/> <b>T\u00ecm c\u00e2u tr\u1ea3 l\u1eddi SAI trong c\u00e1c kh\u1eb3ng \u0111\u1ecbnh d\u01b0\u1edbi \u0111\u00e2y.<\/b> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-07.png' \/><\/center> ","select":["A. $\\widehat{B} = \\widehat{C} = 70^{o} $","B. $\\widehat{ACy} = 100^{o} $ ","C. $\\widehat{xAB} = 110^{o} $ ","D. $\\widehat{xAB} = \\widehat{ACy} $ "],"explain":"<span class='basic_left'> Ta c\u00f3 $AB = AC$ n\u00ean $\\triangle ABC $ c\u00e2n t\u1ea1i A $\\Rightarrow \\widehat{B} = \\widehat{C} $ <br\/> A. \u0110\u00fang. V\u00ec $\\widehat{B} = \\widehat{C} = \\dfrac{180^{o}-\\widehat{A}}{2} = \\dfrac{180^{o}-40^{o}}{2} = 70^{o} $ <br\/> B. Sai. V\u00ec $\\widehat{ACy} = \\widehat{A} + \\widehat{B} = 40^{o} + 70^{o} = 110^{o} $ (g\u00f3c ngo\u00e0i c\u1ee7a tam gi\u00e1c $ABC$) <br\/> C. \u0110\u00fang. V\u00ec $Ax \/\/ By$ n\u00ean $\\widehat{xAC} = \\widehat{C} = 70^{o} $ <br\/> Suy ra: $\\widehat{xAB} = \\widehat{xAC} + \\widehat{A} = 70^{o} + 40^{o} = 110^{o} $ <br\/> D. \u0110\u00fang. $\\widehat{xAB} = \\widehat{ACy} (= 110^{o})$ <br\/><br\/> <span class='basic_pink'> V\u1eady c\u00e2u tr\u1ea3 l\u1eddi sai l\u00e0 B. <\/span> ","column":2}]}],"id_ques":1677},{"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":"<b>T\u00ecm c\u00e2u tr\u1ea3 l\u1eddi sai.<\/b> <br\/> Cho tam gi\u00e1c $DEF$ c\u00f3 $\\widehat{D} = \\widehat{E} = 45^{o} $. Khi \u0111\u00f3: ","select":["A. $\\widehat{F} = 45^{o} $ ","B. $DF = EF $ ","C. $\\widehat{F} = 90^{o}$","D. Tam gi\u00e1c DEF vu\u00f4ng c\u00e2n t\u1ea1i F. "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-11.png' \/><\/center> <span class='basic_left'> C\u00e2u sai l\u00e0 A. V\u00ec: <br\/> Tam gi\u00e1c $DEF$ c\u00f3 $\\widehat{D} = \\widehat{E} = 45^{o} $ <br\/> $\\Rightarrow \\Delta DEF$ vu\u00f4ng c\u00e2n t\u1ea1i F. <br\/> $\\Rightarrow \\widehat{F} = 90^{o} $ <br\/> <span class='basic_pink'>C\u00e2u A l\u00e0 SAI<\/span> ","column":2}]}],"id_ques":1678},{"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 tam gi\u00e1c $RQS$ c\u00e2n t\u1ea1i R c\u00f3 $\\widehat{Q} = 60^{o} $. <br\/> X\u00e9t c\u00e1c kh\u1eb3ng \u0111\u1ecbnh sau: <br\/> (I) $RQ = QS = SR$ <br\/> (II) $\\widehat{R} = \\widehat{Q} = \\widehat{S} = 60^{o} $ ","select":["A. Ch\u1ec9 c\u00f3 (I) \u0111\u00fang. ","B. Ch\u1ec9 c\u00f3 (II) \u0111\u00fang. ","C. C\u1ea3 (I) v\u00e0 (II) \u0111\u1ec1u \u0111\u00fang. ","D. C\u1ea3 (I) v\u00e0 (II) \u0111\u1ec1u sai. "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-12.png' \/><\/center> <span class='basic_left'> Tam gi\u00e1c $RSQ$ c\u00e2n t\u1ea1i R n\u00ean $\\widehat{Q} = \\widehat{S} = 60^{o} $ <br\/> $\\Rightarrow \\widehat{R} = 60^{o} $ <br\/> Hay tam gi\u00e1c $RSQ$ l\u00e0 tam gi\u00e1c \u0111\u1ec1u. <br\/> $\\Rightarrow RQ = QS = SR \\\\ \\widehat{R} = \\widehat{Q} = \\widehat{S} = 60^{o} $ <br\/> V\u1eady c\u1ea3 (I) v\u00e0 (II) \u0111\u1ec1u \u0111\u00fang. <br\/> <br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span> ","column":2}]}],"id_ques":1679},{"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":"T\u00ecm c\u00e2u ph\u00e1t bi\u1ec3u sai. ","select":["A. Tam gi\u00e1c \u0111\u1ec1u l\u00e0 tam gi\u00e1c c\u00f3 ba c\u1ea1nh b\u1eb1ng nhau. ","B. Tam gi\u00e1c \u0111\u1ec1u th\u00ec c\u00f3 ba c\u1ea1nh b\u1eb1ng nhau, ba g\u00f3c b\u1eb1ng nhau. ","C. N\u1ebfu m\u1ed9t tam gi\u00e1c c\u00f3 hai g\u00f3c b\u1eb1ng nhau, hai c\u1ea1nh b\u1eb1ng nhau th\u00ec tam gi\u00e1c \u0111\u00f3 l\u00e0 tam gi\u00e1c \u0111\u1ec1u. "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-13.png' \/><\/center> C\u00e2u sai l\u00e0 C. <br\/> V\u00ed d\u1ee5 tam gi\u00e1c $ABC$ c\u00f3 hai g\u00f3c $\\widehat{B} = \\widehat{C} $, $AB = AC$ <br\/> Nh\u01b0ng tam gi\u00e1c $ABC$ kh\u00f4ng ph\u1ea3i tam gi\u00e1c \u0111\u1ec1u. ","column":1}]}],"id_ques":1680},{"time":24,"part":[{"time":3,"title":"S\u1eafp x\u1ebfp c\u00e1c c\u00e2u","title_trans":"S\u1eafp x\u1ebfp c\u00e1c b\u01b0\u1edbc v\u1ebd tam gi\u00e1c \u0111\u1ec1u $ABC$ c\u00f3 c\u1ea1nh b\u1eb1ng 3cm. ","temp":"sequence","correct":[[[3],[2],[1]]],"list":[{"point":5,"image":"https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-14.png","left":["V\u1ebd c\u00e1c \u0111o\u1ea1n th\u1eb3ng $AB, AC$.","V\u1ebd cung tr\u00f2n t\u00e2m B b\u00e1n k\u00ednh 3cm v\u00e0 cung tr\u00f2n t\u00e2m C b\u00e1n k\u00ednh 3cm, ch\u00fang c\u1eaft nhau t\u1ea1i A. ","V\u1ebd \u0111o\u1ea1n th\u1eb3ng $BC = 3cm$."],"top":80,"explain":" <span class='basic_left'> - V\u1ebd \u0111o\u1ea1n th\u1eb3ng $BC = 3cm.$ <br\/> - V\u1ebd cung tr\u00f2n t\u00e2m B b\u00e1n k\u00ednh 3cm v\u00e0 cung tr\u00f2n t\u00e2m C b\u00e1n k\u00ednh 3cm, ch\u00fang c\u1eaft nhau t\u1ea1i A. <br\/> - V\u1ebd c\u00e1c \u0111o\u1ea1n th\u1eb3ng $AB, AC.$ <\/span> "}]}],"id_ques":1681},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"<span class='basic_left'> <b>Ch\u1ecdn c\u00e2u tr\u1ea3 l\u1eddi sai.<\/b> <br\/> Cho tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A v\u00e0 tam gi\u00e1c $A'B'C'$ c\u00e2n t\u1ea1i A', bi\u1ebft $AB = A'B'$. <br\/> H\u00e3y b\u1ed5 sung th\u00eam m\u1ed9t \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $\\triangle ABC = \\triangle A'B'C' $ ","select":["A. $BC = B'C'$ ","B. $\\widehat{A} = \\widehat{A'} $ ","C. $\\widehat{B} = \\widehat{B'} $ ","D. $AB = B'C' $ "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-15.png' \/><\/center> <span class='basic_left'> Tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A v\u00e0 tam gi\u00e1c $A'B'C'$ c\u00e2n t\u1ea1i A', c\u00f3 $AB = A'B'$ <br\/> $\\Rightarrow AC=A'C'$ <br\/> Khi \u0111\u00f3: $\\Delta ABC$ v\u00e0 $\\Delta A'B'C'$ c\u00f3: <br\/> + $AB=A'B'$ <br\/> + $AC=A'C'$ <br\/> A. \u0110\u00fang. Khi c\u00f3 th\u00eam $BC = B'C'$ th\u00ec ta d\u1ec5 d\u00e0ng ch\u1ec9 ra \u0111\u01b0\u1ee3c: $\\triangle ABC = \\triangle A'B'C' (c.c.c) $ <br\/> B. \u0110\u00fang. Khi c\u00f3 th\u00eam $\\widehat{A} = \\widehat{A'} $ th\u00ec ta d\u1ec5 d\u00e0ng ch\u1ec9 ra \u0111\u01b0\u1ee3c: $\\triangle ABC = \\triangle A'B'C' (c.g.c) $ <br\/> C. \u0110\u00fang. Khi $\\widehat{B} = \\widehat{B'} $ th\u00ec $\\widehat{B} = \\widehat{B'}=\\widehat{C}=\\widehat{C'}$ <br\/> $\\Rightarrow \\widehat{A}=\\widehat{A'}$ <br\/> Khi \u0111\u00f3 $\\triangle ABC = \\triangle A'B'C' (g.c.g)$ <br\/> D. Sai. Kh\u00f4ng \u0111\u1ee7 \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 hai tam gi\u00e1c b\u1eb1ng nhau. <br\/> <span class='basic_pink'> V\u1eady c\u00e2u tr\u1ea3 l\u1eddi sai l\u00e0 D. <\/span> ","column":2}]}],"id_ques":1682},{"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":"Cho h\u00ecnh v\u1ebd. <br\/> Tam gi\u00e1c $GHI$ c\u00e2n t\u1ea1i : <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-16.png' \/><\/center> ","select":[" G "," H "," I "],"explain":"<span class='basic_left'> Tam gi\u00e1c $GHI$ c\u00f3: $\\widehat{G} + \\widehat{H} + \\widehat{I} = 180^{o} \\\\ \\Rightarrow \\widehat{G} = 180^{o} - (70^{o}+40^{o}) = 70^{o}$ <br\/> $\\Rightarrow \\widehat{G} = \\widehat{H} $ <br\/> V\u1eady tam gi\u00e1c $GHI$ c\u00e2n t\u1ea1i I. ","column":3}]}],"id_ques":1683},{"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":"Cho h\u00ecnh v\u1ebd. <br\/> Trong h\u00ecnh c\u00f3 bao nhi\u00eau tam gi\u00e1c c\u00e2n? <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-17a.png' \/><\/center> ","select":[" A. 2 "," B. 3 "," C. 4 ","D. 5"],"explain":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-17.png' \/><\/center><span class='basic_left'> Ta c\u00f3 $OM = ON = MN$ <br\/> $\\Rightarrow \\triangle OMN $ l\u00e0 tam gi\u00e1c \u0111\u1ec1u n\u00ean n\u00f3 c\u0169ng l\u00e0 m\u1ed9t tam gi\u00e1c c\u00e2n (1) <br\/>Do $ MO = MK$ (gi\u1ea3 thi\u1ebft) <br\/> $ \\Rightarrow \\triangle MOK $ c\u00e2n t\u1ea1i M (2)<br\/>Do $NO = NP $ (gi\u1ea3 thi\u1ebft)<br\/> $\\Rightarrow \\triangle NOP $ c\u00e2n t\u1ea1i N (3) <br\/> Ta th\u1ea5y $\\widehat{M_1}$ l\u00e0 g\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh M c\u1ee7a $\\Delta OMK$ n\u00ean: <br\/> $\\widehat{M_1}=\\widehat{K}+\\widehat{O_1}$ <br\/> Hay $\\widehat{K}+\\widehat{O_1}=60^o$ <br\/> M\u00e0 $\\widehat{K}=\\widehat{O_1}$ <br\/> $\\Rightarrow \\widehat{K}=30^o$ <br\/> T\u01b0\u01a1ng t\u1ef1, ta c\u0169ng ch\u1ec9 ra \u0111\u01b0\u1ee3c: $\\widehat{P}=30^o$ <br\/> Do \u0111\u00f3: $\\widehat{K} = \\widehat{P} (= 30^{o}) \\Rightarrow \\triangle OKP $ c\u00e2n t\u1ea1i O (4) <br\/> T\u1eeb (1), (2), (3) v\u00e0 (4) th\u00ec c\u00f3 4 tam gi\u00e1c c\u00e2n trong h\u00ecnh. <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span>","column":4}]}],"id_ques":1684},{"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":"Cho tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A. <br\/> L\u1ea5y c\u00e1c \u0111i\u1ec3m D v\u00e0 E theo th\u1ee9 t\u1ef1 thu\u1ed9c c\u00e1c c\u1ea1nh AB, AC sao cho $AD = AE$. Khi \u0111\u00f3: ","select":[" BE < CD "," BE = CD "," BE > CD "],"explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-19.png' \/><\/center> <span class='basic_left'> Tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A $\\Rightarrow $ $AB = AC$ <br\/> X\u00e9t $\\triangle ABE $ v\u00e0 $\\triangle ACD $ c\u00f3: <br\/> + $AB = AC$ (gi\u1ea3 thi\u1ebft)<br\/> + $\\widehat{A}$ chung<br\/> + $AE = AD$ (gi\u1ea3 thi\u1ebft) <br\/> Do \u0111\u00f3 $\\triangle ABE = \\triangle ACD $ (c.g.c) <br\/> $\\Rightarrow BE = CD $ ","column":3}]}],"id_ques":1685},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["25"]]],"list":[{"point":5,"width":20,"content":"","type_input":"","ques":"Cho h\u00ecnh v\u1ebd: <br\/> S\u1ed1 \u0111o g\u00f3c $\\widehat{DCA} $ l\u00e0: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^{o}$ <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-28.png' \/><\/center> ","hint":"- T\u00ednh s\u1ed1 \u0111o g\u00f3c $\\widehat{ADB} $. <br\/> - D\u1ef1a v\u00e0o tam gi\u00e1c $ADC$ c\u00e2n t\u1ea1i D suy ra s\u1ed1 \u0111o g\u00f3c $\\widehat{DCA} $","explain":"<span class='basic_left'> Tam gi\u00e1c $ABD$ c\u00e2n t\u1ea1i $B\\, (BA = BD)$ n\u00ean $\\widehat{BAD} = \\widehat{BDA} $ <br\/> M\u00e0 $\\widehat{BAD} + \\widehat{BDA} = 180^{o} - \\widehat{ABD} = 180^{o} - 80^{o} = 100^{o}$ <br\/> Suy ra $\\widehat{BAD} = \\widehat{BDA} = \\dfrac{100^{o}}{2} = 50^{o} $ <br\/> Ta c\u00f3 $\\widehat{BDA} = \\widehat{DAC} + \\widehat{DCA} = 50^{o} $ (g\u00f3c ngo\u00e0i c\u1ee7a tam gi\u00e1c $ADC$) (1) <br\/> M\u00e0 tam gi\u00e1c $ADC$ c\u00e2n t\u1ea1i $D\\, (DA = DC)$ n\u00ean $\\widehat{DAC} = \\widehat{DCA} $ (2) <br\/> T\u1eeb (1) v\u00e0 (2) suy ra $\\widehat{DAC} = \\widehat{DCA} = \\dfrac{50^{o}}{2} = 25^{o} $ <br\/> <span class='basic_pink'>V\u1eady $\\widehat{DCA} = 25^{o} $<\/span>"}]}],"id_ques":1686},{"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":"S\u1ed1 \u0111o hai g\u00f3c \u1edf \u0111\u00e1y c\u1ee7a m\u1ed9t tam gi\u00e1c c\u00e2n: ","select":[" $ < 90^{o} $ "," $ = 90^{o} $ "," $ > 90^{o} $ "],"explain":"<span class='basic_left'> X\u00e9t tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A, c\u00f3 $\\widehat{B} = \\widehat{C} $ <br\/> N\u1ebfu $\\widehat{B} \\geq 90^{o} $ th\u00ec $\\widehat{C} \\geq 90^{o}$ n\u00ean $\\widehat{B} + \\widehat{C} \\geq 180^{o} $ (v\u00f4 l\u00ed). <br\/> V\u1eady $\\widehat{B} < 90^{o}, \\widehat{C} < 90^{o} $ ","column":3}]}],"id_ques":1687},{"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 tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i A. K\u1ebb $AH \\perp BC (H \\in BC) $. <br\/> Tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $\\widehat{HAC} $ c\u1eaft BC \u1edf D. <br\/> Tam gi\u00e1c $ABD$ l\u00e0 tam gi\u00e1c g\u00ec? <\/span> ","select":["A. Tam gi\u00e1c c\u00e2n","B. Tam gi\u00e1c \u0111\u1ec1u","C. Tam gi\u00e1c vu\u00f4ng","D. Tam gi\u00e1c vu\u00f4ng c\u00e2n."],"explain":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/hinhhoc/bai13/lv1/img\/H7B13-36.png' \/><\/center><span class='basic_left'> Ta c\u00f3 $\\widehat{A_{1}} + \\widehat{B} = 90^{o} \\\\ \\widehat{C} + \\widehat{B} = 90^{o} \\\\ \\Rightarrow \\widehat{A_{1}} = \\widehat{C} $ <br\/> C\u00f3 AD l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c $\\widehat{HAC} $ n\u00ean $\\widehat{A_{2}} = \\widehat{A_{3}} $ <br\/> M\u1eb7t kh\u00e1c c\u00f3: $ \\widehat{D_{1}} = \\widehat{A_{3}}+ \\widehat{C} $ (g\u00f3c ngo\u00e0i c\u1ee7a tam gi\u00e1c) <br\/> Suy ra $\\widehat{D_{1}} = \\widehat{A_{2}} + \\widehat{A_{1}} $ <br\/> Hay $\\widehat{D_{1}} = \\widehat{BAD} $ <br\/> Tam gi\u00e1c $ABD$ c\u00f3 $\\widehat{D_{1}} = \\widehat{BAD} $ n\u00ean l\u00e0 tam gi\u00e1c c\u00e2n t\u1ea1i B.<br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span>","column":2}]}],"id_ques":1688},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Cho tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A. <br\/> Ph\u00e1t bi\u1ec3u n\u00e0o trong c\u00e1c ph\u00e1t bi\u1ec3u sau l\u00e0 sai. ","select":["A. $\\widehat{B} = \\widehat{C} $","B. $\\widehat{C} = \\dfrac{180^{o}-\\widehat{A}}{2} $ ","C. $\\widehat{A} = 180^{o} - 2\\widehat{C} $ ","D. $\\widehat{B} \\neq \\widehat{C} $"],"explain":"<b>Ph\u00e1t bi\u1ec3u sai l\u00e0 D.<\/b> V\u00ec: <br\/> Tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A th\u00ec $\\widehat{B} = \\widehat{C} $ ","column":2}]}],"id_ques":1689},{"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":"M\u1ed9t tam gi\u00e1c c\u00e2n c\u00f3 g\u00f3c \u1edf \u0111\u1ec9nh b\u1eb1ng $54^{o} $ th\u00ec s\u1ed1 \u0111o g\u00f3c \u1edf \u0111\u00e1y l\u00e0: ","select":["A. $54^{o} $","B. $63^{o} $ ","C. $72^{o} $ ","D. $65^{o} $"],"explain":"<span class='basic_left'> Gi\u1ea3 s\u1eed tam gi\u00e1c $ABC$ c\u00e2n t\u1ea1i A c\u00f3 $\\widehat{A} = 54^{o} $, <br\/> $\\Rightarrow \\widehat{B} = \\widehat{C} $ <br\/> M\u1eb7t kh\u00e1c $\\triangle ABC $ c\u00f3: <br\/> $\\widehat{A} + \\widehat{B} + \\widehat{C} = 180^{o} \\\\ \\Rightarrow \\widehat{A} + 2\\widehat{B} = 180^{o} \\\\ \\Rightarrow \\widehat{B} = \\dfrac{180^{o}-\\widehat{A} }{2} \\\\ = \\dfrac{180^{o}-54^{o}}{2} = \\dfrac{126^{o}}{2} \\\\ = 63^{o} $ <br\/> V\u1eady $ \\widehat{B} = \\widehat{C} = 63^{o} $ <br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span> <\/span> ","column":4}]}],"id_ques":1690}],"lesson":{"save":0,"level":1}}