{"segment":[{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 ho\u1eb7c ch\u1eef th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["C"],["B"],["7"]]],"list":[{"point":10,"width":60,"type_input":"","ques":"<span class='basic_left'>V\u1ebd tam gi\u00e1c ABC, bi\u1ebft ba c\u1ea1nh BC = 12cm, AB = 7cm, AC = 9cm.<br\/><b>C\u00e1ch v\u1ebd:<\/b><br\/>+ V\u1ebd \u0111o\u1ea1n th\u1eb3ng BC = 12cm<br\/>+ V\u1ebd cung tr\u00f2n t\u00e2m _input_, b\u00e1n k\u00ednh 9cm<br\/>+ V\u1ebd cung tr\u00f2n t\u00e2m _input_, b\u00e1n k\u00ednh _input_cm.<br\/>+ L\u1ea5y m\u1ed9t giao \u0111i\u1ec3m c\u1ee7a hai cung tr\u00ean, g\u1ecdi giao \u0111i\u1ec3m \u0111\u00f3 l\u00e0 A<br\/>+ V\u1ebd \u0111o\u1ea1n th\u1eb3ng AB, AC, ta c\u00f3 $\\triangle$ABC.<\/span>","hint":"","explain":"<span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K101.png' \/><\/center><b>C\u00e1ch v\u1ebd:<\/b><br\/>+ V\u1ebd \u0111o\u1ea1n th\u1eb3ng BC = 12cm<br\/>+ V\u1ebd cung tr\u00f2n t\u00e2m C, b\u00e1n k\u00ednh 9cm<br\/>+ V\u1ebd cung tr\u00f2n t\u00e2m B, b\u00e1n k\u00ednh 7cm.<br\/>+ L\u1ea5y m\u1ed9t giao \u0111i\u1ec3m c\u1ee7a hai cung tr\u00ean, g\u1ecdi giao \u0111i\u1ec3m \u0111\u00f3 l\u00e0 A<br\/>+ V\u1ebd \u0111o\u1ea1n th\u1eb3ng AB, AC, ta c\u00f3 $\\triangle$ABC.<br\/>V\u1eady s\u1ed1 ho\u1eb7c ch\u1eef c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng theo th\u1ee9 t\u1ef1 t\u1eeb tr\u00ean xu\u1ed1ng d\u01b0\u1edbi, t\u1eeb tr\u00e1i sang ph\u1ea3i l\u00e0:<span class='basic_pink'> C, B, 7<\/span><\/span> <\/span> <br\/> "}]}],"id_ques":2251},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":"Tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n (O) ta l\u1ea5y m\u1ed9t s\u1ed1 \u0111i\u1ec3m. V\u1ebd c\u00e1c d\u00e2y cung c\u00f3 hai \u0111\u1ea7u l\u00e0 hai trong s\u1ed1 c\u00e1c \u0111i\u1ec3m \u0111\u00e3 cho. Bi\u1ebft r\u1eb1ng c\u00f3 t\u1ea5t c\u1ea3 16 d\u00e2y cung. T\u00ednh s\u1ed1 cung tr\u00f2n \u0111\u00e3 t\u1ea1o th\u00e0nh.","select":["A. 8 cung tr\u00f2n","B. 16 cung tr\u00f2n","C. 32 cung tr\u00f2n","D. 38 cung tr\u00f2n"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Cho n \u0111i\u1ec3m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n. V\u1ebd c\u00e1c d\u00e2y c\u00f3 hai \u0111\u1ea7u l\u00e0 hai trong n \u0111i\u1ec3m \u0111\u00e3 cho. Khi \u0111\u00f3:<br\/>+ S\u1ed1 d\u00e2y t\u1ea1o th\u00e0nh \u0111\u01b0\u1ee3c t\u00ednh theo c\u00f4ng th\u1ee9c: $\\dfrac{n.(n - 1)}{2}$<br\/>+ S\u1ed1 cung tr\u00f2n \u0111\u01b0\u1ee3c t\u1ea1o th\u00e0nh \u0111\u01b0\u1ee3c t\u00ednh theo c\u00f4ng th\u1ee9c: n . (n - 1) ( ho\u1eb7c s\u1ed1 cung tr\u00f2n = s\u1ed1 d\u00e2y cung . 2)<\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> S\u1ed1 cung tr\u00f2n t\u1ea1o th\u00e0nh l\u00e0:<br\/>16 . 2 = 32 (cung tr\u00f2n)<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'>C. 32 cung tr\u00f2n<\/span><\/span> <br\/>","column":2}]}],"id_ques":2252},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":" Cho hai $\\widehat{xOy}$ v\u00e0 $\\widehat{yOz}$ k\u1ec1 b\u00f9. Bi\u1ebft $\\widehat{xOy}$ = $110^o$. G\u1ecdi Om l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c yOz. S\u1ed1 \u0111o c\u1ee7a g\u00f3c xOm l\u00e0:","select":["A. $70^o$","B. $80^o$","C. $145^o$","D. $150^o$"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K103.png' \/><\/center> Ta c\u00f3: $\\widehat{xOy}$ v\u00e0 $\\widehat{yOz}$ k\u1ec1 b\u00f9<br\/>Do \u0111\u00f3: $\\widehat{xOy}$ + $\\widehat{yOz}$ = $\\widehat{xOz}$ = $180^o$<br\/>Thay $\\widehat{xOy}$ = $110^o$ ta \u0111\u01b0\u1ee3c: <br\/>$110^o$ + $\\widehat{yOz}$ = $180^o$<br\/>Suy ra $\\widehat{yOz}$ = $180^o$ - $110^o$ = $70^o$<br\/>+ Om l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c yOz<br\/>Do \u0111\u00f3: $\\widehat{yOm}$ = $\\widehat{mOz}$ = $\\dfrac{1}{2}$ $\\widehat{yOz}$ = $\\dfrac{1}{2}$.$70^o$ = $35^o$<br\/>+ $\\widehat{mOz}$ < $\\widehat{zOx}$ ( v\u00ec $35^o$ < $180^o$) n\u00ean tia Om n\u1eb1m gi\u1eefa hai tia Oz v\u00e0 Ox<br\/>Suy ra: $\\widehat{xOm}$ + $\\widehat{mOz}$ = $\\widehat{xOz}$<br\/>Thay $\\widehat{zOm}$ = $35^o$, $\\widehat{xOz}$ = $180^o$ ta \u0111\u01b0\u1ee3c:<br\/>$35^o$ + $\\widehat{xOm}$ = $180^o$<br\/>$\\widehat{xOm}$ = $180^o$ - $35^o$ = $145^o$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'>C. $145^o$<\/span><\/span> <br\/><\/span><\/span><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span><br\/>Oy l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c xOz khi:<br\/>+ Tia Oy l\u00e0 tia n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<br\/>+ $\\widehat{xOy}$ = $\\widehat{yOz}$ <\/span>","column":2}]}],"id_ques":2253},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K105.png' \/><\/center> Cho h\u00ecnh v\u1ebd c\u00f3 s\u1ed1 \u0111o nh\u01b0 tr\u00ean. T\u00ednh $\\widehat{yOz}$. ","select":["A. $\\widehat{yOz}$ = $60^o$","B. $\\widehat{yOz}$ = $70^o$","C. $\\widehat{yOz}$ = $80^o$","D. $\\widehat{yOz}$ = $90^o$"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K105.png' \/><\/center>Ta c\u00f3: $\\widehat{xOy}$ < $\\widehat{xOz}$ ( v\u00ec $35^o$ < $180^o$)<br\/> N\u00ean tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<br\/>Suy ra $\\widehat{xOy}$ + $\\widehat{yOz}$ = $\\widehat{xOz}$<br\/>Thay $\\widehat{xOy}$ = $35^o$, $\\widehat{xOz}$ = $115^o$, ta \u0111\u01b0\u1ee3c:<br\/> $35^o$ + $\\widehat{yOz}$ = $115^o$ <br\/>Suy ra $\\widehat{yOz}$ = $115^o$ - $35^o$ = $80^o$ <br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'>C. <\/span>$\\widehat{yOz}$ = $80^o$<\/span> <br\/><\/span><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span> $\\widehat{xOy}$ = $m^o$, $\\widehat{xOz}$ = $n^o$. N\u1ebfu $m^o$ < $n^o$ th\u00ec tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<\/span>","column":2}]}],"id_ques":2254},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K107.png' \/><\/center> Cho h\u00ecnh v\u1ebd c\u00f3 s\u1ed1 \u0111o nh\u01b0 tr\u00ean. T\u00ednh $\\widehat{xOy}$. ","select":["A. $\\widehat{xOy}$ = $75^o$","B. $\\widehat{xOy}$ = $85^o$","C. $\\widehat{xOy}$ = $145^o$","D. $\\widehat{xOy}$ = $155^o$"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K107.png' \/><\/center>Ta c\u00f3: $\\widehat{zOy}$ < $\\widehat{zOx}$ ( v\u00ec $45^o$ < $130^o$)<br\/> N\u00ean tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<br\/>Suy ra $\\widehat{xOy}$ + $\\widehat{yOz}$ = $\\widehat{xOz}$<br\/>Thay $\\widehat{yOz}$ = $45^o$, $\\widehat{xOz}$ = $130^o$, ta \u0111\u01b0\u1ee3c:<br\/> $\\widehat{xOy}$ + $45^o$= $130^o$ <br\/>Suy ra $\\widehat{xOy}$ = $130^o$ - $45^o$ = $85^o$ <br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'>B. <\/span>$\\widehat{yOz}$ = $85^o$<\/span> <br\/><\/span><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span> $\\widehat{xOy}$ = $m^o$, $\\widehat{xOz}$ = $n^o$. N\u1ebfu $m^o$ < $n^o$ th\u00ec tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<\/span>","column":2}]}],"id_ques":2255},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K109.png' \/><\/center> Cho h\u00ecnh v\u1ebd c\u00f3 s\u1ed1 \u0111o nh\u01b0 tr\u00ean. Bi\u1ebft tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz. T\u00ednh $\\widehat{xOz}$ ","select":["A. $\\widehat{xOz}$ = $55^o$","B. $\\widehat{xOz}$ = $65^o$","C. $\\widehat{xOz}$ = $75^o$","D. $\\widehat{xOz}$ = $85^o$"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz th\u00ec: $\\widehat{xOy}$ + $\\widehat{yOz}$ = $\\widehat{xOz}$<\/span> <br\/><br\/><span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K109.png' \/><\/center>Ta c\u00f3: Tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<br\/> N\u00ean $\\widehat{xOy}$ + $\\widehat{yOz}$ = $\\widehat{xOz}$<br\/>Thay $\\widehat{xOy}$ = $45^o$, $\\widehat{yOz}$ = $30^o$, ta \u0111\u01b0\u1ee3c:<br\/> $\\widehat{xOz}$ = $45^o$ + $30^o$ = $75^o$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: C. $\\widehat{xOz}$ = $75^o$<\/span> <br\/><\/span>","column":2}]}],"id_ques":2256},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":" Tr\u00ean c\u00f9ng m\u1ed9t n\u1eeda m\u1eb7t ph\u1eb3ng b\u1edd c\u00f3 ch\u1ee9a tia Ox, v\u1ebd hai tia Oy v\u00e0 Oz sao cho $\\widehat{xOy}$ = $40^o$, $\\widehat{xOz}$ = $80^o$. H\u00e3y ch\u1ecdn c\u00e2u \u0111\u00fang nh\u1ea5t:","select":["A. Tia Oy l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c xOz","B. $\\widehat{yOz}$ = $40^o$","C. Tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz","D. T\u1ea5t c\u1ea3 c\u00e1c \u0111\u00e1p \u00e1n A, B, C \u0111\u1ec1u \u0111\u00fang"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K111.png' \/><\/center>Ta c\u00f3: $\\widehat{xOy}$ < $\\widehat{xOz}$ (v\u00ec $40^o$ < $80^o$)<br\/>N\u00ean <b>tia Oy n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<\/b> (1)<br\/>Suy ra $\\widehat{xOy}$ + $\\widehat{yOz}$ = $\\widehat{xOz}$ <br\/>Thay $\\widehat{xOy}$ = $40^o$, $\\widehat{xOz}$ = $80^o$, ta \u0111\u01b0\u1ee3c:<br\/> $40^o$ + $\\widehat{yOz}$ = $80^o$<br\/>$\\widehat{yOz}$ = $80^o$ - $40^o$ = $40^o$<br\/>M\u00e0 $\\widehat{xOy}$ = $40^o$ n\u00ean <b>$\\widehat{xOy}$ = $\\widehat{yOz}$<\/b> (2)<br\/>T\u1eeb (1) v\u00e0 (2) suy ra <b>tia Oy l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c xOz<\/b><br\/>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t l\u00e0: <span class='basic_pink'>D. T\u1ea5t c\u1ea3 c\u00e1c \u0111\u00e1p \u00e1n A, B, C \u0111\u1ec1u \u0111\u00fang<\/span><\/span> <br\/><\/span><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span><br\/>Oy l\u00e0 tia ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c xOz khi:<br\/>+ Tia Oy l\u00e0 tia n\u1eb1m gi\u1eefa hai tia Ox v\u00e0 Oz<br\/>+ $\\widehat{xOy}$ = $\\widehat{yOz}$ <\/span>","column":2}]}],"id_ques":2257},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" Cho 8 tia chung g\u1ed1c. S\u1ed1 g\u00f3c t\u1ea1o th\u00e0nh l\u00e0:","select":["A. 25 g\u00f3c","B. 28 g\u00f3c","C. 30 g\u00f3c","D. 32 g\u00f3c"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Cho n tia chung g\u1ed1c, m\u1ed7i tia t\u1ea1o v\u1edbi n - 1 tia c\u00f2n l\u1ea1i th\u00e0nh n - 1 g\u00f3c. C\u00f3 n tia n\u00ean t\u1ea1o \u0111\u01b0\u1ee3c n.(n - 1) g\u00f3c. Nh\u01b0ng m\u1ed7i g\u00f3c \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00ednh hai l\u1ea7n, do \u0111\u00f3 t\u1ea5t c\u1ea3 ch\u1ec9 c\u00f3: $\\dfrac{n . (n - 1)}{2}$ g\u00f3c<br\/> <b>V\u1eady g\u1ecdi n l\u00e0 s\u1ed1 tia chung g\u1ed1c, khi \u0111\u00f3 s\u1ed1 g\u00f3c do n tia n\u00e0y t\u1ea1o ra \u0111\u01b0\u1ee3c t\u00ednh theo c\u00f4ng th\u1ee9c: $\\dfrac{n . (n - 1)}{2}$<\/b><\/span> <br\/><br\/><span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3: <br\/>S\u1ed1 g\u00f3c t\u1ea1o th\u00e0nh l\u00e0: $\\dfrac{8. (8 - 1)}{2}$ = 28 (g\u00f3c)<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0:<span class='basic_pink'>B. 28 g\u00f3c<\/span><\/span> <br\/><\/span><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span><br\/>G\u1ecdi n l\u00e0 s\u1ed1 tia chung g\u1ed1c, khi \u0111\u00f3 s\u1ed1 g\u00f3c do n tia n\u00e0y t\u1ea1o ra \u0111\u01b0\u1ee3c t\u00ednh theo c\u00f4ng th\u1ee9c: $\\dfrac{n . (n - 1)}{2}$<\/b><\/span>","column":2}]}],"id_ques":2258},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":" Bi\u1ebft $\\widehat{xOy}$ = $25^o$, $\\widehat{aOb}$ = $65^o$. V\u1eady hai g\u00f3c xOy v\u00e0 aOb l\u00e0 hai g\u00f3c: ","select":["A. b\u00f9 nhau","B. k\u1ec1 nhau","C. k\u1ec1 b\u00f9","D. ph\u1ee5 nhau"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3: <br\/>$\\widehat{xOy}$ + $\\widehat{aOb}$ = $25^o$ + $65^o$ = $90^o$<br\/>Suy ra hai g\u00f3c xOy v\u00e0 aOb l\u00e0 hai g\u00f3c ph\u1ee5 nhau<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'>D. ph\u1ee5 nhau<\/span><\/span> <br\/><\/span><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span> Hai g\u00f3c ph\u1ee5 nhau l\u00e0 hai g\u00f3c c\u00f3 t\u1ed5ng s\u1ed1 \u0111o b\u1eb1ng $90^o$<\/span>","column":2}]}],"id_ques":2259},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" Cho $\\widehat{BOC}$ = $75^o$. A l\u00e0 m\u1ed9t \u0111i\u1ec3m n\u1eb1m trong g\u00f3c BOC. Bi\u1ebft $\\widehat{BOA}$ = $45^o$. V\u1ebd tia OD l\u00e0 tia \u0111\u1ed1i c\u1ee7a tia OA. So s\u00e1nh $\\widehat{BOD}$ v\u00e0 $\\widehat{COD}$. ","select":["A. $\\widehat{BOD}$ > $\\widehat{COD}$","B. $\\widehat{BOD}$ < $\\widehat{COD}$","C. $\\widehat{BOD}$ = $\\widehat{COD}$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>B\u01b0\u1edbc 1: T\u00ednh $\\widehat{COA}$<br\/>B\u01b0\u1edbc 2: T\u00ednh $\\widehat{COD}$<br\/>B\u01b0\u1edbc 3: T\u00ednh $\\widehat{BOD}$<br\/>B\u01b0\u1edbc 4: So s\u00e1nh $\\widehat{BOD}$ v\u00e0 $\\widehat{COD}$<\/span> <br\/><br\/><span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/ontapchuong/lv3/img\/H626_K126.png' \/><\/center>V\u00ec \u0111i\u1ec3m A n\u1eb1m trong g\u00f3c BOC n\u00ean tia OA n\u1eb1m gi\u1eefa hai tia OB v\u00e0 OC, do \u0111\u00f3:<br\/>$\\widehat{BOA}$ + $\\widehat{AOC}$ = $\\widehat{BOC}$<br\/>Thay $\\widehat{BOA}$ = $50^o$, $\\widehat{BOC}$ = $75^o$ ta \u0111\u01b0\u1ee3c:<br\/>$50^o$ + $\\widehat{AOC}$ = $75^o$<br\/>Suy ra $\\widehat{AOC}$ = $75^o$ - $50^o$ = $25^o$<br\/>V\u00ec OD l\u00e0 tia \u0111\u1ed1i c\u1ee7a tia OA n\u00ean c\u00e1c g\u00f3c AOB v\u00e0 BOD; AOC v\u00e0 COD l\u00e0 hai g\u00f3c k\u1ec1 b\u00f9, do \u0111\u00f3:<br\/>$\\widehat{AOB}$ + $\\widehat{BOD}$ = $180^o$, suy ra $50^o$ + $\\widehat{BOD}$ = $180^o$, hay $\\widehat{BOD}$ = $180^o$ - $50^o$ = $130^o$ <b>(1)<\/b><br\/>$\\widehat{AOC}$ + $\\widehat{COD}$ = $180^o$, suy ra $25^o$ + $\\widehat{COD}$ = $180^o$, hay $\\widehat{COD}$ = $180^o$ - $25^o$ = $155^o$ <b>(2)<\/b><br\/>T\u1eeb (1) v\u00e0 (2) suy ra $\\widehat{BOD}$ < $\\widehat{COD}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'>B. <\/span>$\\widehat{BOD}$ < $\\widehat{COD}$<\/span> <br\/><\/span>","column":3}]}],"id_ques":2260}],"lesson":{"save":0,"level":3}}