{"segment":[{"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":" Trong c\u00e1c h\u00ecnh sau, h\u00ecnh n\u00e0o l\u00e0 t\u1ee9 gi\u00e1c: ","select":["A. <img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1a.jpg' \/> ","B. <img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1b.jpg' \/> ","C. <img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1c.jpg' \/>","D. <img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1d.jpg' \/> "],"hint":" \u0110\u1ebfm s\u1ed1 \u0111o\u1ea1n th\u1eb3ng c\u1ee7a c\u00e1c h\u00ecnh \u0111\u1ec3 t\u00ecm ra h\u00ecnh n\u00e0o l\u00e0 t\u1ee9 gi\u00e1c. <br\/> T\u1ee9 gi\u00e1c l\u00e0 h\u00ecnh c\u00f3 4 \u0111o\u1ea1n th\u1eb3ng, trong \u0111\u00f3 b\u1ea5t k\u00ec hai \u0111o\u1ea1n th\u1eb3ng n\u00e0o c\u0169ng kh\u00f4ng c\u00f9ng n\u1eb1m tr\u00ean m\u1ed9t \u0111\u01b0\u1eddng th\u1eb3ng. ","explain":" H\u00ecnh A c\u00f3 3 \u0111o\u1ea1n th\u1eb3ng <br\/> H\u00ecnh B c\u00f3 4 \u0111o\u1ea1n th\u1eb3ng <br\/> H\u00ecnh C c\u00f3 6 \u0111o\u1ea1n th\u1eb3ng <br\/> H\u00ecnh D l\u00e0 h\u00ecnh tr\u00f2n. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B. <\/span><\/span> ","column":4}]}],"id_ques":1281},{"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_random","correct":[[["AC","CA"],["BD","DB"]]],"list":[{"point":5,"width":40,"type_input":"","ques":" Cho t\u1ee9 gi\u00e1c sau: <br\/> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_2.jpg' \/><\/center> <br\/> <br\/> <b> C\u00e2u 1:<\/b> T\u1ee9 gi\u00e1c $ABCD$ c\u00f3 hai \u0111\u01b0\u1eddng ch\u00e9o l\u00e0 _input_ v\u00e0 _input_ ","hint":" \u0110\u01b0\u1eddng ch\u00e9o l\u00e0 \u0111o\u1ea1n th\u1eb3ng n\u1ed1i hai \u0111\u1ec9nh \u0111\u1ed1i nhau","explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_2b.jpg' \/><\/center> Hai \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a t\u1ee9 gi\u00e1c $ABCD$ l\u00e0 $AC$ v\u00e0 $BD$. <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $AC; BD$ <\/span><\/span> "}]}],"id_ques":1282},{"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_random","correct":[[["AB","BA"],["BC","CB"],["AD","DA"],["DC","CD"]]],"list":[{"point":5,"width":40,"type_input":"","ques":" Cho t\u1ee9 gi\u00e1c sau: <br\/> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_2.jpg' \/><\/center> <br\/> <br\/> <b> C\u00e2u 2:<\/b> T\u1ee9 gi\u00e1c $ABCD$ c\u00f3 b\u1ed1n c\u1ea1nh l\u00e0 _input_ ; _input_ ; _input_ v\u00e0 _input_ ","hint":" C\u1ea1nh c\u1ee7a t\u1ee9 gi\u00e1c l\u00e0 \u0111o\u1ea1n n\u1ed1i hai \u0111\u1ec9nh k\u1ec1 nhau.","explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_2.jpg' \/><\/center> B\u1ed1n c\u1ea1nh c\u1ee7a t\u1ee9 gi\u00e1c $ABCD$ l\u00e0 $AB; BC; CD$ v\u00e0 $AD$. <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $AB; BC; CD$ v\u00e0 $AD$ <\/span><\/span> "}]}],"id_ques":1283},{"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":" Trong m\u1ed9t t\u1ee9 gi\u00e1c c\u00f3 nhi\u1ec1u nh\u1ea5t: ","select":["A. 1 g\u00f3c vu\u00f4ng ","B. 2 g\u00f3c vu\u00f4ng ","C. 3 g\u00f3c vu\u00f4ng","D. 4 g\u00f3c vu\u00f4ng "],"hint":" Gi\u1ea3 s\u1eed c\u1ea3 4 g\u00f3c \u0111\u1ec1u l\u00e0 vu\u00f4ng, so s\u00e1nh t\u1ed5ng c\u1ee7a 4 g\u00f3c \u0111\u00f3 v\u1edbi $360^o$ ","explain":" <span class='basic_left'> G\u1ecdi $n$ l\u00e0 s\u1ed1 g\u00f3c vu\u00f4ng trong m\u1ed9t t\u1ee9 gi\u00e1c $(n>0)$. <br\/> Ta \u0111i t\u00ecm gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t c\u1ee7a $n$. <br\/> Ta c\u00f3: <br\/> $9.n \\le 360^o$ <br\/> $\\Rightarrow n \\le 4$ <br\/> $\\Rightarrow n_{max}=4$ <br\/> Do \u0111\u00f3 trong m\u1ed9t t\u1ee9 gi\u00e1c c\u00f3 nhi\u1ec1u nh\u1ea5t l\u00e0 4 g\u00f3c vu\u00f4ng. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D. <\/span><\/span> ","column":4}]}],"id_ques":1284},{"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":" Trong m\u1ed9t t\u1ee9 gi\u00e1c, t\u1ed5ng s\u1ed1 \u0111o c\u00e1c g\u00f3c l\u00e0: ","select":["A. $360^o$ ","B. $180^o$ ","C. $240^o$","D. $300^o$ "],"explain":" Theo \u0111\u1ecbnh l\u00fd, t\u1ed5ng c\u00e1c g\u00f3c trong m\u1ed9t t\u1ee9 gi\u00e1c l\u00e0 $360^o$. <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A. <\/span><\/span> ","column":4}]}],"id_ques":1285},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["50"]]],"list":[{"point":5,"width":40,"type_input":"","ques":" Cho t\u1ee9 gi\u00e1c $ABCD$ trong h\u00ecnh sau: <br\/> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_3.jpg' \/><\/center> $x =$ _input_ $^o$ ","hint":" T\u1ed5ng c\u00e1c g\u00f3c trong t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$, t\u1eeb \u0111\u00f3 t\u00ednh ra $x$. ","explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_3.jpg' \/><\/center> Trong t\u1ee9 gi\u00e1c $ABCD$, ta c\u00f3:<br\/> $\\begin{align} & \\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}={{360}^{o}} \\\\ \\Rightarrow\\,\\,& {{120}^{o}}+{{80}^{o}}+x+{{110}^{o}}={{360}^{o}} \\\\ & \\Rightarrow {{310}^{o}}+x={{360}^{o}} \\\\ & \\Rightarrow x={{360}^{o}}-{{310}^{o}} \\\\ & \\Rightarrow x={{50}^{o}} \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $50$. <\/span><\/span> "}]}],"id_ques":1286},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["80"]]],"list":[{"point":5,"width":40,"type_input":"","ques":" Cho t\u1ee9 gi\u00e1c $ABCD$ trong h\u00ecnh sau: <br\/> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_4.jpg' \/><\/center> $x =$ _input_ $^o$ ","hint":" T\u1ed5ng c\u00e1c g\u00f3c trong t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$, t\u1eeb \u0111\u00f3 t\u00ednh ra $x$. ","explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_4.jpg' \/><\/center> Trong t\u1ee9 gi\u00e1c $ABCD$, ta c\u00f3:<br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}={{360}^{o}}$ (\u0110\u1ecbnh l\u00fd)<br\/>$\\begin{align} \\Rightarrow\\,\\, & {{120}^{o}}+{{80}^{o}}+x+x={{360}^{o}} \\\\ & \\Rightarrow {{200}^{o}}+2x={{360}^{o}} \\\\ & \\Rightarrow 2x={{360}^{o}}-{{200}^{o}} \\\\ & \\Rightarrow 2x={{160}^{o}} \\\\ & \\Rightarrow x={{80}^{o}} \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $80$. <\/span><\/span> "}]}],"id_ques":1287},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["60"]]],"list":[{"point":5,"width":40,"type_input":"","ques":" Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}=90^o;\\,\\,\\widehat{B}=2x;\\,\\,\\widehat{C}=90^o;\\,\\,\\widehat{D}=x$. T\u00ednh $x$. <br\/> <br\/> <b>\u0110\u00e1p \u00e1n:<\/b> $x =$ _input_ $^o$ ","hint":" T\u1ed5ng c\u00e1c g\u00f3c trong t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$, t\u1eeb \u0111\u00f3 t\u00ednh ra $x$. ","explain":" Trong t\u1ee9 gi\u00e1c $ABCD$, ta c\u00f3: <br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}={{360}^{o}}$ (\u0110\u1ecbnh l\u00fd)<br\/> $\\begin{align} \\Rightarrow \\,\\,& 90^o+2x+90^o+x={{360}^{o}} \\\\ & \\Rightarrow 180^o+3x={{360}^{o}} \\\\ & \\Rightarrow 3x=360^o-180^o \\\\ & \\Rightarrow 3x={{180}^{o}} \\\\ & \\Rightarrow x={{60}^{o}} \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $60$. <\/span><\/span> "}]}],"id_ques":1288},{"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":[[["200"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ trong h\u00ecnh sau <br\/> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_5.jpg' \/><\/center> C\u00f3 $\\widehat{A}=100^o; \\widehat{C}=60^o;AB=AD; BC=CD$ <br\/> <br\/> <b> C\u00e2u 1:<\/b> T\u00ednh $\\widehat{B} +\\widehat{D}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{B}+\\widehat{D}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":" T\u1ed5ng c\u00e1c g\u00f3c trong t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$, t\u1eeb \u0111\u00f3 t\u00ednh ra t\u1ed5ng hai g\u00f3c $B$ v\u00e0 $D$. ","explain":" <span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_5.jpg' \/><\/center> Trong t\u1ee9 gi\u00e1c $ABCD$, ta c\u00f3: <br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}={{360}^{o}}$ (\u0110\u1ecbnh l\u00fd) <br\/> $\\begin{align} & \\Rightarrow {{100}^{o}}+\\widehat{B}+60^o+\\widehat{D}={{360}^{o}} \\\\ & \\Rightarrow {{160}^{o}}+\\widehat{B}+\\widehat{D}={{360}^{o}} \\\\ & \\Rightarrow \\widehat{B}+\\widehat{D}={{360}^{o}}-{{160}^{o}} \\\\ & \\Rightarrow \\widehat{B}+\\widehat{D}={{200}^{o}} \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $200$. <\/span><\/span> "}]}],"id_ques":1289},{"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":[[["100"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ trong h\u00ecnh sau: <br\/> <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_5.jpg' \/><\/center> C\u00f3 $\\widehat{A}=100^o; \\widehat{C}=60^o;AB=AD; BC=CD$ <br\/> <br\/> <b> C\u00e2u 2:<\/b> T\u00ednh $\\widehat{B}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{B}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":" Ch\u1ee9ng minh $ \\widehat{B} =\\widehat{D}$","explain":" <span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_5.jpg' \/><\/center> Theo b\u00e0i ra: $AB = AD$ n\u00ean $ABD$ l\u00e0 tam gi\u00e1c c\u00e2n t\u1ea1i $A$.<br\/> $\\Rightarrow \\widehat{B_2}=\\widehat{D_2}$ (1) <br\/> T\u01b0\u01a1ng t\u1ef1: $BC = CD$ n\u00ean $BDC$ l\u00e0 tam gi\u00e1c c\u00e2n t\u1ea1i $C$ <br\/> $\\Rightarrow \\widehat{B_1}=\\widehat{D_1}$ (2)<br\/> T\u1eeb (1) v\u00e0 (2) suy ra $ \\widehat{B}=\\widehat{D}$ <br\/> M\u00e0 $\\widehat{B}+\\widehat{D}=200^o$ (theo c\u00e2u 1) <br\/> $\\Rightarrow \\widehat{B}=\\widehat{D}=200^o:2=100^o$<br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $100$. <\/span><\/span> "}]}],"id_ques":1290},{"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":[[["60"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}=130^o; \\widehat{B}=90^o$. G\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh $C$ c\u00f3 s\u1ed1 \u0111o l\u00e0 $120^o$. <br\/> <br\/> <b> C\u00e2u 1:<\/b> T\u00ednh $\\widehat{BCD}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{BCD}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":" G\u1ecdi $\\widehat{BCD}$ l\u00e0 g\u00f3c $\\widehat{C_1}$ <br\/> Khi \u0111\u00f3 hai g\u00f3c $\\widehat{DCx}$ v\u00e0 $\\widehat{C_1}$ k\u1ec1 b\u00f9 nhau. ","explain":" <span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_6.jpg' \/><\/center>G\u1ecdi $\\widehat{BCD}$ l\u00e0 g\u00f3c $\\widehat{C_1}$ <br\/> Do hai g\u00f3c $\\widehat{DCx}$ v\u00e0 $\\widehat{C_1}$ k\u1ec1 b\u00f9 nhau n\u00ean:<br\/> $\\begin{align} & \\widehat{DCx}+\\widehat{C_1}={{180}^{o}} \\\\ & \\Rightarrow 120^o+\\widehat{C_1}={{180}^{o}} \\\\ & \\Rightarrow \\widehat{C_1}={{180}^{o}}-120^o \\\\ & \\Rightarrow \\widehat{C_1}=60^o \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $60$. <\/span><\/span> "}]}],"id_ques":1291},{"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":[[["80"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}=130^o; \\widehat{B}=90^o$. G\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh $C$ c\u00f3 s\u1ed1 \u0111o l\u00e0 $120^o$. <br\/> <br\/> <b> C\u00e2u 2:<\/b> T\u00ednh $\\widehat{D}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{D}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":" T\u1ed5ng c\u00e1c g\u00f3c trong m\u1ed9t t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$ ","explain":" <span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_6.jpg' \/><\/center> Theo c\u00e2u 1, ta t\u00ednh \u0111\u01b0\u1ee3c $\\widehat{C_1}=60^o$. <br\/> Trong t\u1ee9 gi\u00e1c $ABCD$, ta c\u00f3:<br\/> $\\begin{align} & \\widehat{A}+\\widehat{B}+\\widehat{C_1}+\\widehat{D}={{360}^{o}} \\\\ & \\Rightarrow {{130}^{o}}+90^o+60^o+\\widehat{D}={{360}^{o}} \\\\ & \\Rightarrow 280^o+\\widehat{D}={{360}^{o}} \\\\ & \\Rightarrow \\widehat{D}={{360}^{o}}-{{280}^{o}} \\\\ & \\Rightarrow \\widehat{D}={{80}^{o}} \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $80$. <\/span><\/span> "}]}],"id_ques":1292},{"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":[[["210"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> T\u1ee9 gi\u00e1c $EFGH$ c\u00f3 $\\widehat{E}={{70}^{o}};\\,\\,\\widehat{F}={{80}^{o}}$. <br\/> <br\/> <b> C\u00e2u 1:<\/b> T\u00ednh $\\widehat{G}+\\widehat{H}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{G}+\\widehat{H}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":"T\u1ed5ng c\u00e1c g\u00f3c trong m\u1ed9t t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$, t\u1eeb \u0111\u00f3 t\u00ecm t\u1ed5ng hai g\u00f3c $G$ v\u00e0 $H$ ","explain":" <span class='basic_left'> Trong t\u1ee9 gi\u00e1c $EFGH$, ta c\u00f3: <br\/> $\\widehat{E}+\\widehat{F}+\\widehat{G}+\\widehat{H}={{360}^{o}}$ (\u0111\u1ecbnh l\u00fd t\u1ed5ng b\u1ed1n g\u00f3c trong m\u1ed9t t\u1ee9 gi\u00e1c) <br\/> $\\begin{align} & \\Rightarrow 70^o+80^o+\\widehat{G}+\\widehat{H}={{360}^{o}} \\\\ & \\Rightarrow \\widehat{G}+\\widehat{H}=360^o-150^o \\\\ & \\Rightarrow \\widehat{G}+\\widehat{H}={{210}^{o}} \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $210$. <\/span><\/span> "}]}],"id_ques":1293},{"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":[[["115"],["95"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> T\u1ee9 gi\u00e1c $EFGH$ c\u00f3 $\\widehat{E}={{70}^{o}};\\,\\,\\widehat{F}={{80}^{o}}$. <br\/> <br\/> <b> C\u00e2u 2:<\/b> Bi\u1ebft r\u1eb1ng $\\widehat{G}-\\widehat{H}={{20}^{o}}$<br\/> T\u00ednh $\\widehat{G};\\,\\,\\widehat{H}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> <br\/> $\\widehat{G}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <br\/> $\\widehat{H}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":" T\u00ednh s\u1ed1 \u0111o hai g\u00f3c G v\u00e0 H khi bi\u1ebft t\u1ed5ng v\u00e0 hi\u1ec7u hai g\u00f3c \u0111\u00f3. ","explain":" <span class='basic_left'> Theo c\u00e2u 1, ta t\u00ednh \u0111\u01b0\u1ee3c $\\widehat{G}+\\widehat{H}={{210}^{o}}$ <br\/> M\u00e0 $\\widehat{G}-\\widehat{H}={{20}^{o}}$ <br\/> $\\Rightarrow \\widehat{G}=\\dfrac{{{210}^{o}}+{{20}^{o}}}{2}={{115}^{o}}$<br\/>$\\widehat{H}=\\dfrac{{{210}^{o}}-{{20}^{o}}}{2}={{95}^{o}}$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $115$ v\u00e0 $95$ <\/span><\/span> "}]}],"id_ques":1294},{"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\u1ed5ng c\u00e1c g\u00f3c ngo\u00e0i c\u1ee7a m\u1ed9t t\u1ee9 gi\u00e1c b\u1eb1ng ","select":["A. $360^o$ ","B. $270^o$ ","C. $180^o$","D. $720^o$ "],"hint":"S\u1eed d\u1ee5ng t\u00ednh ch\u1ea5t: T\u1ed5ng s\u1ed1 \u0111o hai g\u00f3c trong v\u00e0 ngo\u00e0i t\u1ea1i m\u1ed9t \u0111\u1ec9nh b\u1eb1ng $180^o$. (do hai g\u00f3c \u1edf v\u1ecb tr\u00ed k\u1ec1 b\u00f9)","explain":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_15.jpg' \/><\/center> <span class='basic_left'>Trong t\u1ee9 gi\u00e1c $ABCD$, g\u1ecdi $\\widehat{A_1}; \\widehat{B_1}; \\widehat{C_1}; \\widehat{D_1}$ l\u00e0 c\u00e1c g\u00f3c trong t\u1ea1i c\u00e1c \u0111\u1ec9nh $A, B, C, D$ c\u1ee7a t\u1ee9 gi\u00e1c. <br\/> G\u1ecdi $\\widehat{A_2}; \\widehat{B_2}; \\widehat{C_2}; \\widehat{D_2}$ l\u00e0 c\u00e1c g\u00f3c ngo\u00e0i t\u1ea1i c\u00e1c \u0111\u1ec9nh $A, B, C, D$. <br\/> Do hai g\u00f3c trong v\u00e0 ngo\u00e0i t\u1ea1i m\u1ed9t \u0111\u1ec9nh k\u1ec1 b\u00f9 nhau, n\u00ean ta c\u00f3:<br\/> $\\widehat{A_1}+ \\widehat{A_2}=180^o$ (1) <br\/> $\\widehat{B_1}+ \\widehat{B_2}=180^o$ (2) <br\/> $\\widehat{C_1}+ \\widehat{C_2}=180^o$ (3) <br\/> $\\widehat{D_1}+ \\widehat{D_2}=180^o$ (4) <br\/> C\u1ed9ng v\u1ebf v\u1edbi v\u1ebf c\u1ee7a (1); (2); (3) v\u00e0 (4) ta \u0111\u01b0\u1ee3c:<br\/> $\\widehat{A_1}+ \\widehat{B_1}+ \\widehat{C_1}+ \\widehat{D_1} + \\widehat{A_2} + \\widehat{B_2} + \\widehat{C_2} + \\widehat{D_2} = 720^o$<br\/> $360^o+ \\widehat{A_2} + \\widehat{B_2} + \\widehat{C_2} + \\widehat{D_2} =720^o$ <br\/> $\\widehat{A_2} + \\widehat{B_2} + \\widehat{C_2} + \\widehat{D_2}=360^o$ <br\/> V\u1eady t\u1ed5ng c\u00e1c g\u00f3c ngo\u00e0i c\u1ee7a m\u1ed9t t\u1ee9 gi\u00e1c b\u1eb1ng $360^o$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <br\/> <\/span><\/span> ","column":4}]}],"id_ques":1295},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t.<br\/> Kh\u1eb3ng \u0111\u1ecbnh d\u01b0\u1edbi \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> T\u1ee9 gi\u00e1c $MNPQ$ c\u00f3 $\\widehat{M}:\\widehat{N}:\\widehat{P}:\\widehat{Q}=1:3:4:7$ th\u00ec <br\/> $\\widehat{M}={{24}^{o}};\\,\\,\\widehat{N}={{72}^{o}};\\,\\,\\widehat{P}={{96}^{o}};\\,\\widehat{Q}={{168}^{o}}$ <\/span> ","select":["\u0110\u00fang","Sai"],"hint":" \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau. ","explain":"<span class='basic_left'> Trong t\u1ee9 gi\u00e1c $MNPQ$ th\u00ec: <br\/> $\\widehat{M}+\\widehat{N}+\\widehat{P}+\\widehat{Q}={{360}^{o}}$<br\/> M\u00e0 theo b\u00e0i $\\widehat{M}:\\widehat{N}:\\widehat{P}:\\widehat{Q}=1:3:4:7$ <br\/> $\\Rightarrow \\dfrac{\\widehat{M}}{1}=\\dfrac{\\widehat{N}}{3}=\\dfrac{\\widehat{P}}{4}=\\dfrac{\\widehat{Q}}{7} $ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau, ta \u0111\u01b0\u1ee3c: <br\/> $ \\widehat{M}:\\widehat{N}:\\widehat{P}:\\widehat{Q}=1:3:4:7 $<br\/>$ \\dfrac{\\widehat{M}}{1}=\\dfrac{\\widehat{N}}{3}=\\dfrac{\\widehat{P}}{4}=\\dfrac{\\widehat{Q}}{7} $$ =\\dfrac{\\widehat{M}+\\widehat{N}+\\widehat{P}+\\widehat{Q}}{1+3+4+7}=\\dfrac{{{360}^{o}}}{15}={{24}^{o}} $<br\/>$ \\Rightarrow \\left\\{ \\begin{align} & \\widehat{M}={{24}^{o}} \\\\ & \\widehat{N}={{24}^{o}}.3={{72}^{o}} \\\\ & \\widehat{P}={{24}^{o}}.4={{96}^{o}} \\\\ & \\widehat{Q}={{24}^{o}}.7={{168}^{o}} \\\\ \\end{align} \\right. $<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang.<\/span>","column":2}]}],"id_ques":1296},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t.<br\/> Kh\u1eb3ng \u0111\u1ecbnh d\u01b0\u1edbi \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> T\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}:\\widehat{B}:\\widehat{C}:\\widehat{D}=2:4:6:8$ th\u00ec $\\widehat{A}={{72}^{o}};\\,\\,\\widehat{D}={{288}^{o}}$ <\/span> ","select":["\u0110\u00fang","Sai"],"hint":" \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau. ","explain":"<span class='basic_left'> Trong t\u1ee9 gi\u00e1c $ABCD$ th\u00ec: <br\/> $\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}={{360}^{o}}$<br\/> M\u00e0 theo b\u00e0i $\\widehat{A}:\\widehat{B}:\\widehat{C}:\\widehat{D}=2:4:6:8$ <br\/> $\\Rightarrow \\dfrac{\\widehat{A}}{2}=\\dfrac{\\widehat{B}}{4}=\\dfrac{\\widehat{C}}{6}=\\dfrac{\\widehat{D}}{8} $ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau, ta \u0111\u01b0\u1ee3c: <br\/> $ \\widehat{A}:\\widehat{B}:\\widehat{C}:\\widehat{D}=2:4:6:8 $<br\/>$ \\dfrac{\\widehat{A}}{2}=\\dfrac{\\widehat{B}}{4}=\\dfrac{\\widehat{C}}{6}=\\dfrac{\\widehat{D}}{8} $$ =\\dfrac{\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}}{2+4+6+8}=\\dfrac{{{360}^{o}}}{20}={{18}^{o}} $<br\/>$ \\Rightarrow \\left\\{ \\begin{align} & \\widehat{A}={{18}^{o}}.2=36^o \\\\ & \\widehat{B}={{18}^{o}}.4={{72}^{o}} \\\\ & \\widehat{C}={{18}^{o}}.6={{108}^{o}} \\\\ & \\widehat{D}={{18}^{o}}.8={{144}^{o}} \\\\ \\end{align} \\right. $<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai.<\/span>","column":2}]}],"id_ques":1297},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["8"],["20"],["16"],["32"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> T\u1ee9 gi\u00e1c c\u00f3 \u0111\u1ed9 d\u00e0i c\u00e1c c\u1ea1nh l\u00e0 $a, b, c$ v\u00e0 $d$. <br\/> Bi\u1ebft chu vi c\u1ee7a t\u1ee9 gi\u00e1c \u0111\u00f3 l\u00e0 $76\\, cm$ v\u00e0 $a:b:c:d=2:5:4:8$ th\u00ec <br\/> $\\left\\{ \\begin{align} & a=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\,\\, cm \\\\ & b=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\,\\, cm \\\\ & c=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\,\\, cm \\\\ & d=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\,\\, cm \\\\ \\end{align} \\right.$ <\/span>","hint":" \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau cho $a:b:c:d=2:5:4:8$ ","explain":" <span class='basic_left'> T\u1eeb $a:b:c:d=2:5:4:8$, ta c\u00f3:<br\/> $\\dfrac{a}{2}=\\dfrac{b}{5}=\\dfrac{c}{4}=\\dfrac{d}{8}$$=\\dfrac{a+b+c+d}{2+5+4+8}=\\dfrac{76}{19}=4$ <br\/> $\\Rightarrow \\left\\{ \\begin{align} & a=4.2=8\\,\\,(cm) \\\\ & b=4.5=20\\,\\,(cm)\\\\ & c=4.4=16\\,\\,(cm) \\\\ & d=4.8=32\\,\\,(cm)\\\\ \\end{align} \\right. $ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $\\left\\{ \\begin{align} & a=8\\,\\, cm \\\\ & b=20 \\,\\, cm \\\\ & c=16 \\,\\, cm \\\\ & d=32\\,\\, cm \\\\ \\end{align} \\right.$ <\/span><\/span> "}]}],"id_ques":1298},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["100"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}={{130}^{o}};\\,\\,\\widehat{B}={{90}^{o}}$, g\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh $C$ b\u1eb1ng ${{120}^{o}}$. T\u00ednh s\u1ed1 \u0111o g\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh $D$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n:<\/b> $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":"T\u00ecm s\u1ed1 \u0111o g\u00f3c trong t\u1ea1i \u0111\u1ec9nh $C$, sau \u0111\u00f3 t\u00ednh s\u1ed1 \u0111o g\u00f3c $D$. ","explain":" <span class='basic_left'> V\u1ebd h\u00ecnh <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_8.jpg' \/><\/center>Ta c\u00f3 $\\widehat{BCD}+\\widehat{DCx}={{180}^{o}}$ (k\u1ec1 b\u00f9) <br\/> $\\Rightarrow \\widehat{BCD}={{180}^{o}}-{{120}^{o}}={{60}^{o}}$ <br\/> X\u00e9t t\u1ee9 gi\u00e1c $ABCD$ ta c\u00f3 : <br\/>$\\widehat{A}+\\widehat{B}+\\widehat{C}+\\widehat{D}={{360}^{o}}$ (\u0111\u1ecbnh l\u00fd t\u1ed5ng 4 g\u00f3c trong 1 t\u1ee9 gi\u00e1c) <br\/>$\\Rightarrow {{130}^{o}}+{{90}^{o}}+{{60}^{o}}+\\widehat{D}={{360}^{o}}$<br\/>$\\Rightarrow \\widehat{D}={{80}^{o}}$ <br\/> S\u1ed1 \u0111o g\u00f3c ngo\u00e0i t\u1ea1i \u0111\u1ec9nh D l\u00e0:<br\/> $180^o-80^o=100^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $100$ <\/span><\/span> "}]}],"id_ques":1299},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["35"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'> Cho t\u1ee9 gi\u00e1c $ABCD$ c\u00f3 $\\widehat{A}={{100}^{o}};\\,\\,\\widehat{D}={{75}^{o}}; \\, \\widehat{ABD}=40^o$.<br\/> T\u00ednh $\\widehat{BDC}$. <br\/> <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $\\widehat{BDC}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}^o$ <\/span>","hint":" X\u00e9t trong tam gi\u00e1c $ABD$ \u0111\u1ec3 t\u00ecm s\u1ed1 \u0111o $\\widehat{BDA}$, sau \u0111\u00f3 t\u00ednh $\\widehat{BDC}$ ","explain":" <span class='basic_left'> V\u1ebd h\u00ecnh <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/hinhhoc/bai1/lv1/img\/H811_D1_9.jpg' \/><\/center> X\u00e9t tam gi\u00e1c $ABD$ c\u00f3: <br\/> $\\widehat{A}+\\widehat{ABD}+\\widehat{BDA}=180^o$ <br\/> $100^o+40^o+\\widehat{BDA}=180^o$ <br\/> $ \\widehat{BDA}=180^o-140^o$<br\/> $\\widehat{BDA}=40^o$ <br\/> M\u00e0 $\\widehat{ADC}=\\widehat{BDA}+\\widehat{BDC}$<br\/>$\\widehat{BDC}=75^o-40^o=35^o$ <br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $35$ <\/span><\/span> "}]}],"id_ques":1300}],"lesson":{"save":0,"level":1}}