{"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":"S\u1eafp x\u1ebfp c\u00e1c t\u1ec9 s\u1ed1 l\u01b0\u1ee3ng gi\u00e1c sau theo th\u1ee9 t\u1ef1 t\u0103ng d\u1ea7n: <br\/> $sin 64^{o}$, $cos 23^{o}$, $sin 53^{o}$, $cos 12^{o}$","select":["A. $sin\\, 64^{o},$ $sin\\, 53^{o},$ $cos\\, 23^{o},$ $cos\\, 12^{o},$ ","B. $sin\\, 53^{o},$ $sin\\, 64^{o},$ $cos\\, 12^{o},$ $cos\\, 23^{o},$ ","C. $sin\\, 53^{o},$ $sin\\, 64^{o},$ $cos\\, 23^{o},$ $cos\\, 12^{o},$","D. $cos\\, 23^{o},$ $cos\\, 12 ^{o},$ $sin\\, 53^{o},$ $sin\\, 64^{o},$ "],"hint":" \u0110\u01b0a c\u00e1c t\u1ec9 s\u1ed1 l\u01b0\u1ee3ng gi\u00e1c \u0111\u00e3 cho v\u1ec1 c\u00f9ng t\u1ec9 s\u1ed1 sin ho\u1eb7c cos: \u00c1p d\u1ee5ng: $sin\\,(90-x)=cos\\,x$","explain":" <span class='basic_left'> Ta c\u00f3:<br\/>$ cos\\, 23^{o}= sin \\,67^{o}$; $\\,\\,\\, cos\\, 12^{o}$ = $sin\\, 78^{o}$ (t\u1ec9 s\u1ed1 l\u01b0\u1ee3ng gi\u00e1c c\u1ee7a hai g\u00f3c ph\u1ee5 nhau)<br\/>V\u00ec $53^o<64^o<67^o<78^o \\Rightarrow sin \\,53^{o}$ $ < sin\\, 64^{o}$ $< sin\\, 67^{o}$ $< sin\\, 78^{o}$ (sin c\u1ee7a g\u00f3c nh\u1ecdn l\u1edbn h\u01a1n th\u00ec l\u1edbn h\u01a1n) <br\/> Suy ra: $sin\\, 53^{o}$$ < sin\\, 64^{o}$$ < cos\\, 23^{o}$$ < cos \\,12^{o}$<br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C <\/span> <\/span>","column":2}]}],"id_ques":1311},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"V\u1edbi g\u00f3c nh\u1ecdn $\\alpha$ t\u00f9y \u00fd, ta c\u00f3: $\\,tg\\,\\alpha.cotg\\,\\alpha=-1$","select":["A. \u0110\u00fang ","B. Sai "],"hint":"X\u00e9t m\u1ed9t tam gi\u00e1c vu\u00f4ng c\u00f3 g\u00f3c nh\u1ecdn \u03b1 \u0111\u1ec3 ki\u1ec3m tra \u0111\u1eb3ng th\u1ee9c \u0111\u00e3 cho.","explain":" <span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D23.png' \/><\/center> Ta c\u00f3: $tg\\,\\alpha=\\dfrac{AC}{AB}\\\\cotg\\,\\alpha=\\dfrac{AB}{AC}\\\\ \\Rightarrow tg\\,\\alpha.cotg\\,\\alpha=\\dfrac{AC}{AB}.\\dfrac{AB}{AC}=1$<br\/>V\u1eady kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 Sai.<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B<\/span> <\/span>","column":2}]}],"id_ques":1312},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $\\dfrac{3}{5}$","B. $\\dfrac{3}{7}$","C. $\\dfrac{5}{7}$"],"ques":"N\u1ebfu $tg\\,\\alpha=\\dfrac{3}{4}$$\\,\\,$ th\u00ec $\\,sin\\,\\alpha=$?","explain":"<img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D22.png' \/><br\/> <span class='basic_left'> D\u1ef1ng tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $A$, $AB=3, AC=4$.<br\/>Ta c\u00f3: $\\,tg\\,\\alpha=tg\\,{C}\\,$$=\\dfrac{AB}{AC}=\\dfrac{3}{4}$<br\/> $\\Delta ABC$ vu\u00f4ng t\u1ea1i $A.$ \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago ta c\u00f3: <br\/> $BC^2=AB^2+AC^2<br\/>\\Rightarrow BC^2=3^2+4^2$<br\/>$\\Rightarrow BC^2=25$ <br\/>$\\Rightarrow BC= 5\\\\ \\Rightarrow\\, sin\\,\\alpha=\\dfrac{AB}{BC}=\\dfrac{3}{5}$<\/span>"}]}],"id_ques":1313},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"N\u1ebfu $sin\\,\\alpha=\\dfrac{1}{4}$$\\,\\,$ th\u00ec $\\,cos\\,\\alpha$ b\u1eb1ng:","select":["A. $\\dfrac{\\sqrt{15}}{4}$ ","B. $\\dfrac{\\sqrt{17}}{4}$ ","C. $\\dfrac{\\sqrt{3}}{4}$","D. $\\dfrac{\\sqrt{5}}{4}$ "],"explain":"<span class='basic_left'><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D19.png' \/><br\/> D\u1ef1ng tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $A$, $AB=1, BC=4$.(L\u1ea5y m\u1ed9t \u0111o\u1ea1n th\u1eb3ng l\u00e0m \u0111\u01a1n v\u1ecb)<br\/>Ta c\u00f3: $\\,sin\\,\\alpha=sin\\,{C}\\,$$=\\dfrac{AB}{BC}=\\dfrac{1}{4}$ <br\/> Ch\u1ecdn $AB = 1 $$\\Rightarrow BC = 4$ <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago ta c\u00f3: <br\/> $BC^2=AB^2+AC^2$<br\/>$\\Rightarrow AC^2=4^2-1^2$<br\/> $\\Rightarrow AC^2=15$<br\/>$\\Rightarrow AC= \\sqrt{15}$<br\/>$ \\Rightarrow\\, cos\\,\\alpha=\\dfrac{AC}{BC}=\\dfrac{\\sqrt{15}}{4}$<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><br\/><span class='basic_green'>L\u01b0u \u00fd:<\/span> Ngo\u00e0i ra, ta c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng \u0111\u1eb3ng th\u1ee9c $sin^2{\\alpha}+cos^2{\\alpha}=1$ \u0111\u1ec3 t\u00ecm $sin \\,\\alpha,$ khi bi\u1ebft gi\u00e1 tr\u1ecb $cos\\,\\alpha$<\/span>","column":4}]}],"id_ques":1314},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"select":["A. $3\\sqrt{13}$","B. $2\\sqrt{13}$","C. $\\sqrt{13}$"],"ques":"Cho h\u00ecnh v\u1ebd:<br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D17.png' \/> <center><br\/> \u0110\u1ed9 d\u00e0i $HC$ l\u00e0: ?","hint":"T\u00ednh c\u1ea1nh $AH$.","explain":"<span class='basic_left'>X\u00e9t $\\Delta AHB$ c\u00f3: $\\widehat{H}=90^o$ <br\/> $tg\\,B=\\dfrac{AH}{BH}$ <br\/> $\\Rightarrow AH=BH.tg\\,60^o=2\\sqrt{3}$ <br\/> X\u00e9t $\\Delta AHC$ c\u00f3: $\\widehat{H}=90^o$.<br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago ta c\u00f3: <br\/> $\\Rightarrow AC^2=AH^2+HC^2$ <br\/> $\\Rightarrow HC^2=5^2-(2\\sqrt{3})^2=13 $ <br\/> $\\Rightarrow HC= \\sqrt{13}$<\/span>"}]}],"id_ques":1315},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["8"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":"Cho h\u00ecnh v\u1ebd: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D16.png' \/><center> \u0110\u1ed9 d\u00e0i c\u1ea1nh $BH$ l\u00e0: _input_","hint":"T\u00ednh c\u1ea1nh $AH$","explain":"<span class='basic_left'>X\u00e9t $\\Delta AHC$ c\u00f3: $\\widehat{H}=90^o$ <br\/> $tg\\,C=\\dfrac{AH}{HC}$ <br\/> $\\Rightarrow AH=HC.tg\\,45^o=6$ <br\/>X\u00e9t $\\Delta AHB$ c\u00f3: $\\widehat{H}=90^o$. <br\/> Theo \u0111\u1ecbnh l\u00ed Pytago ta c\u00f3: <br\/> $\\Rightarrow AB^2=AH^2+HB^2$ <br\/> $\\Rightarrow HB^2=10^2-6^2=64 $ <br\/> $ \\Rightarrow HB= 8$ <br\/><span class='basic_pink'>V\u1eady k\u1ebft qu\u1ea3 c\u1ea7n \u0111i\u1ec1n l\u00e0 $8$.<\/span><\/span>"}]}],"id_ques":1316},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $\\dfrac{8}{15}$","B. $\\dfrac{7}{15}$","C. $\\dfrac{4}{15}$"],"ques":"Cho h\u00ecnh v\u1ebd, t\u00ednh $tg\\,C$<br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D13.png' \/><center> \u0110\u00e1p s\u1ed1: $tg\\,C=$?","hint":"\u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago \u0111\u1ec3 t\u00ednh c\u1ea1nh $AC$","explain":"<span class='basic_left'> X\u00e9t $\\Delta ABC$ c\u00f3: $\\widehat{A}=90^o$. <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago ta c\u00f3: <br\/>$BC^2=AB^2+AC^2\\\\ \\Rightarrow AC^2=17^2-8^2\\\\ \\Rightarrow AC^2=225\\\\ \\Rightarrow AC=15 $<br\/>Khi \u0111\u00f3 $tg\\,C=\\dfrac{AB}{AC}=\\dfrac{8}{15}$<\/span> "}]}],"id_ques":1317},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"select":["A. $\\dfrac{8}{13}$","B. $\\dfrac{5}{13}$","C. $\\dfrac{4}{13}$"],"ques":"Cho h\u00ecnh v\u1ebd, t\u00ednh $sin\\, C$<br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D11.png' \/><center> \u0110\u00e1p s\u1ed1: $sin\\,C=$?","hint":"\u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago \u0111\u1ec3 t\u00ednh c\u1ea1nh $BC$","explain":"X\u00e9t $\\Delta ABC$ c\u00f3: $\\widehat{A}=90^o$. <br\/> \u00c1p d\u1ee5ng \u0111\u1ecbnh l\u00ed Pytago ta c\u00f3: <br\/> $BC^2=AB^2+AC^2\\\\ \\Rightarrow BC^2=5^2+12^2\\\\ \\Rightarrow BC^2=169\\\\ \\Rightarrow BC=13$<br\/>Suy ra $sin\\,C=\\dfrac{AB}{BC}=\\dfrac{5}{13}$ <\/span>"}]}],"id_ques":1318},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $2\\sqrt{3}$","B. $3\\sqrt{3}$","C. $4\\sqrt{3}$"],"ques":"Cho h\u00ecnh v\u1ebd:<br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D9.png' \/><center> \u0110\u1ed9 d\u00e0i c\u1ea1nh $DF$ l\u00e0: ?","explain":"<span class='basic_left'> X\u00e9t $\\Delta DEF$ c\u00f3: $\\widehat{D}={{90}^{o}}$ <br\/>$tg \\,F=\\dfrac{DE}{DF}\\,$ <br\/> $\\Rightarrow tg \\,{{60}^{o}}=\\dfrac{6}{DF}\\,$ <br\/> $\\Rightarrow DF=\\dfrac{6}{\\sqrt{3}}=2\\sqrt{3}$"}]}],"id_ques":1319},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"select":["A. $\\sqrt{2}$","B. $2\\sqrt{2}$","C. $\\dfrac{\\{8}sqrt{2}}{2}$"],"ques":"Cho h\u00ecnh v\u1ebd:<br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D8.png' \/><center> \u0110\u1ed9 d\u00e0i c\u1ea1nh $BC$ l\u00e0: ?","explain":"<span class='basic_left'> X\u00e9t $\\Delta ABC$ c\u00f3: $\\widehat{A}={{90}^{o}}$ <br\/> $\\cos \\,B=\\dfrac{AB}{BC}\\,$ <br\/> $\\Rightarrow \\cos {{45}^{o}}=\\dfrac{4}{BC}\\,$ <br\/> $\\Rightarrow BC=\\dfrac{4}{\\dfrac{\\sqrt{2}}{2}}=\\dfrac{\\{8}sqrt{2}}$"}]}],"id_ques":1320},{"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":"H\u00ecnh v\u1ebd d\u1ef1ng g\u00f3c nh\u1ecdn $\\beta$ sao cho $\\,tg\\,\\beta=\\dfrac{3}{2}$ l\u00e0: ","select":["A. <img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D5a.png' \/>","B. <img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D5b.png' \/>","C. <img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D5c2.png' \/>"],"hint":"$tg\\,\\beta=\\dfrac{c\u1ea1nh \\,\\,\u0111\u1ed1i}{c\u1ea1nh \\,\\,k\u1ec1}$","explain":"<span class='basic_left'>D\u1ef1ng g\u00f3c vu\u00f4ng $xOy$. L\u1ea5y m\u1ed9t \u0111o\u1ea1n th\u1eb3ng l\u00e0m \u0111\u01a1n v\u1ecb. <br\/> Tr\u00ean tia $Ox$ l\u1ea5y \u0111i\u1ec3m $B$ sao cho $OB=3$ <br\/> Tr\u00ean tia $Oy$ l\u1ea5y \u0111i\u1ec3m $A$ sao cho $OA= 2$ <br\/> G\u00f3c $OAB$ l\u00e0 g\u00f3c $\\beta$ c\u1ea7n d\u1ef1ng.<br\/>Th\u1eadt v\u1eady, ta c\u00f3 $tg\\,\\beta=tg\\,\\widehat {OAB}=\\dfrac {OB}{OA}=\\dfrac {3}{2}$<br\/><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D5d.png' \/><br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C<\/span><\/span>","column":4}]}],"id_ques":1321},{"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":"H\u00ecnh v\u1ebd d\u1ef1ng g\u00f3c nh\u1ecdn $\\alpha$ sao cho $\\,cos\\,\\alpha=\\dfrac{3}{5}$ l\u00e0: ","select":["A. <img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D3a.png' \/>","B. <img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D3b.png' \/>","C. <img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D3c.png' \/>"],"hint":"$cos\\,\\alpha=\\dfrac{c\u1ea1nh \\,\\,k\u1ec1}{c\u1ea1nh \\,\\,huy\u1ec1n}$","explain":"<span class='basic_left'>D\u1ef1ng g\u00f3c vu\u00f4ng $xOy$. L\u1ea5y m\u1ed9t \u0111o\u1ea1n th\u1eb3ng l\u00e0m \u0111\u01a1n v\u1ecb.<br\/> Tr\u00ean tia $Ox$ l\u1ea5y \u0111i\u1ec3m $A$ sao cho $OA=3$ <br\/> D\u1ef1ng \u0111\u01b0\u1eddng tr\u00f2n $(A; 5)$ c\u1eaft tia $Oy$ t\u1ea1i $B$ <br\/> G\u00f3c $BAO$ l\u00e0 g\u00f3c c\u1ea7n d\u1ef1ng.<br\/>Th\u1eadt v\u1eady, ta c\u00f3 $cos\\,\\alpha=cos\\,\\widehat {BAO}=\\dfrac {OA}{AB}=\\dfrac {3}{5}$ <br\/><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D3d.png' \/><br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B<\/span><\/span>","column":4}]}],"id_ques":1322},{"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":"Cho h\u00ecnh v\u1ebd, h\u1ec7 th\u1ee9c n\u00e0o sau \u0111\u00e2y l\u00e0 \u0111\u00fang? <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D2.png' \/><\/center> ","select":["A. $sin\\,\\alpha=\\dfrac{x}{z}$","B. $cos\\,\\alpha=\\dfrac{z}{y}$ ","C. $tg\\,\\alpha=\\dfrac{x}{z}$","D. $cotg\\,\\alpha=\\dfrac{y}{z}$"],"explain":" <span class='basic_left'> $sin\\,\\alpha=\\dfrac{x}{z};\\,\\,\\,\\,\\,cos\\,\\alpha=\\dfrac{y}{z}\\\\ tg\\,\\alpha=\\dfrac{x}{y};\\,\\,\\,\\,\\,cotg\\,\\alpha=\\dfrac{y}{x}$ <br\/> V\u1eady h\u1ec7 th\u1ee9c \u0111\u00fang l\u00e0 $sin\\,\\alpha=\\dfrac{x}{z}$ <br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A<\/span> <\/span>","column":4}]}],"id_ques":1323},{"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, h\u1ec7 th\u1ee9c n\u00e0o sau \u0111\u00e2y \u0111\u00fang? <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/H912_D1.png' \/><\/center> ","select":["A. $sin\\,\\alpha=\\dfrac{m}{n}$","B. $cos\\,\\alpha=\\dfrac{n}{m}$ ","C. $tg\\,\\alpha=\\dfrac{m}{p}$","D. $cotg\\,\\alpha=\\dfrac{n}{m}$"],"explain":" <span class='basic_left'> $sin\\,\\alpha=\\dfrac{m}{p};\\,\\,\\,\\,\\,cos\\,\\alpha=\\dfrac{n}{p}\\\\ tg\\,\\alpha=\\dfrac{m}{n};\\,\\,\\,\\,\\,cotg\\,\\alpha=\\dfrac{n}{m}$ <br\/> V\u1eady h\u1ec7 th\u1ee9c \u0111\u00fang l\u00e0 $cotg\\,\\alpha=\\dfrac{n}{m}$ <br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D<\/span><\/span>","column":4}]}],"id_ques":1324},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["40"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":"<span class='basic_left'>D\u00f9ng b\u1ea3ng l\u01b0\u1ee3ng gi\u00e1c ho\u1eb7c m\u00e1y t\u00ednh b\u1ecf t\u00fai \u0111\u1ec3 t\u00ecm s\u1ed1 \u0111o g\u00f3c nh\u1ecdn $x$ (l\u00e0m tr\u00f2n \u0111\u1ebfn \u0111\u1ed9), bi\u1ebft r\u1eb1ng : $\\,cotg \\,x=1,1918$<br\/>\u0110\u00e1p s\u1ed1: $x=$ _input_$^o$<\/span>","explain":"$x=40^o$<br\/><span class='basic_pink'>V\u1eady k\u1ebft qu\u1ea3 c\u1ea7n \u0111i\u1ec1n l\u00e0 $40$<\/span>"}]}],"id_ques":1325},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u <, > , = th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["="]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/5.jpg' \/><\/center>So s\u00e1nh: sin 33$^o$_input_ cos 57$^o$","hint":"N\u1ebfu hai g\u00f3c ph\u1ee5 nhau th\u00ec sin g\u00f3c n\u00e0y b\u1eb1ng c\u00f4sin g\u00f3c kia, tang g\u00f3c n\u00e0y b\u1eb1ng c\u00f4tang g\u00f3c kia","explain":"<span class='basic_left'> Do $33^o$ v\u00e0 $57^o$ l\u00e0 hai g\u00f3c ph\u1ee5 nhau <br\/> $\\Rightarrow sin\\, 33^o = cos\\,57^o$ <br\/><span class='basic_pink'>V\u1eady k\u1ebft qu\u1ea3 c\u1ea7n \u0111i\u1ec1n l\u00e0 = <\/span> <\/span>"}]}],"id_ques":1326},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u $<, > , =$ th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["<"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/5.jpg' \/><\/center> <br\/>So s\u00e1nh: $sin\\, 20^o$_input_ $cos \\,40^o$","hint":"\u0110\u01b0a hai gi\u00e1 tr\u1ecb c\u1ea7n so s\u00e1nh v\u1ec1 c\u00f9ng gi\u00e1 tr\u1ecb cos ho\u1eb7c sin","explain":"<span class='basic_left'>Ta c\u00f3: $sin\\, 20^o$ $= cos\\, 70^o$ <br\/> V\u00ec $70^o>40^o\\Rightarrow cos\\, 70^o< cos \\,40^o$ <br\/> Suy ra, $sin\\, 20^o< cos 40 ^o$ <br\/> <span class='basic_pink'>V\u1eady k\u1ebft qu\u1ea3 c\u1ea7n \u0111i\u1ec1n l\u00e0 $<$ <\/span><br\/><span class='basic_green'>L\u01b0u \u00fd:<\/span>S\u1ed1 \u0111o g\u00f3c nh\u1ecdn c\u00e0ng l\u1edbn th\u00ec gi\u00e1 tr\u1ecb sin c\u00e0ng l\u1edbn, gi\u00e1 tr\u1ecb cosin c\u00e0ng nh\u1ecf<\/span>"}]}],"id_ques":1327},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $\\sqrt{3}$","B. $\\sqrt{2}$","C. $2\\sqrt{2}$"],"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/4.jpg' \/><\/center> $tg\\, 60^o=$?","explain":"$tg\\,60^o = \\sqrt{3}$"}]}],"id_ques":1328},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $\\dfrac{1}{2}$","B. $\\dfrac{1}{4}$","C. $\\dfrac{1}{3}$"],"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai2/lv1/img\/2.jpg' \/><\/center> $sin\\, 30^o=$?","explain":" $sin\\,30^o=\\dfrac{1}{2}$ "}]}],"id_ques":1329},{"time":24,"part":[{"time":3,"title":"H\u00e3y gh\u00e9p m\u1ed7i \u00f4 \u1edf c\u1ed9t tr\u00e1i v\u1edbi m\u1ed9t \u00f4 \u1edf c\u1ed9t ph\u1ea3i \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1ed9t kh\u1eb3ng \u0111\u1ecbnh \u0111\u00fang","title_trans":"","audio":"","temp":"matching","correct":[["3","1","2"]],"list":[{"point":5,"image":"","left":["T\u1ec9 s\u1ed1 gi\u1eefa c\u1ea1nh \u0111\u1ed1i v\u00e0 c\u1ea1nh huy\u1ec1n","T\u1ec9 s\u1ed1 gi\u1eefa c\u1ea1nh k\u1ec1 v\u00e0 c\u1ea1nh huy\u1ec1n","T\u1ec9 s\u1ed1 gi\u1eefa c\u1ea1nh \u0111\u1ed1i v\u00e0 c\u1ea1nh k\u1ec1"],"right":["\u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u00f4sin c\u1ee7a g\u00f3c $\\,\\alpha$, k\u00ed hi\u1ec7u l\u00e0 $cos\\,\\alpha$","\u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 tang c\u1ee7a g\u00f3c $\\,\\alpha$, k\u00ed hi\u1ec7u l\u00e0 $tg\\,\\alpha$","\u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 sin c\u1ee7a g\u00f3c $\\,\\alpha$, k\u00ed hi\u1ec7u l\u00e0 $sin\\,\\alpha$"],"top":100,"explain":"<span class='basic_left'>T\u1ec9 s\u1ed1 gi\u1eefa c\u1ea1nh \u0111\u1ed1i v\u00e0 c\u1ea1nh huy\u1ec1n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 sin c\u1ee7a g\u00f3c $\\alpha$, k\u00ed hi\u1ec7u l\u00e0 sin$\\alpha$ <br\/> T\u1ec9 s\u1ed1 gi\u1eeda c\u1ea1nh k\u1ec1 v\u00e0 c\u1ea1nh huy\u1ec1n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u00f4sin c\u1ee7a g\u00f3c $\\,\\alpha$, k\u00ed hi\u1ec7u l\u00e0 cos$\\alpha$ <br\/> T\u1ec9 s\u1ed1 gi\u1eefa c\u1ea1nh \u0111\u1ed1i v\u00e0 c\u1ea1nh k\u1ec1 \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 tang c\u1ee7a g\u00f3c $\\,\\alpha$, k\u00ed hi\u1ec7u l\u00e0 tg$\\alpha$<\/span>"}]}],"id_ques":1330}],"lesson":{"save":0,"level":1}}