{"common":{"save":0,"post_id":"998","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"1721","post_id":"998","mon_id":"0","chapter_id":"0","question":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","options":{"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":"<span class='basic_left'><b>T\u00ecm c\u00e2u tr\u1ea3 l\u1eddi sai: <\/b><br\/> Cho h\u00ecnh v\u1ebd, bi\u1ebft: <br\/> $ AB = 1cm, BC = \\sqrt{2} cm , \\widehat{ADC} = 45^{o} $. Khi \u0111\u00f3: <center><img src='img\/H7B14-03.png' \/><\/center> ","select":["A. $\\widehat{ABC} = \\widehat{ACB} = \\widehat{CAD} $","B. $\\widehat{BAC} = 90^{o}, \\widehat{BAD} = 135^{o} $","C. $AB \/\/ CD, AD \/\/ BC $ ","D. $AD = CD = 1cm $ "],"explain":" <span class='basic_left'> <center><img src='img\/H7B14-03.png' \/><\/center> Ta c\u00f3 $\\triangle ABC $ vu\u00f4ng t\u1ea1i A n\u00ean theo \u0111\u1ecbnh l\u00ed Py-ta-go c\u00f3: <br\/> $BC^{2} = AB^{2} + AC^{2} \\\\ \\Rightarrow AC^{2} = BC^{2} - AB^{2} \\\\ = (\\sqrt{2})^{2} - (1)^{2} \\\\ = 1^{2} \\\\ \\Rightarrow AC = 1 cm $ <br\/> C\u00f3 $AB = AC = 1cm$ n\u00ean $\\triangle ABC $ vu\u00f4ng c\u00e2n t\u1ea1i A (1) <br\/> M\u00e0 trong $\\Delta ADC$ vu\u00f4ng t\u1ea1i C v\u00e0 c\u00f3 $\\widehat{ADC}=45^o$ (gi\u1ea3 thi\u1ebft) <br\/> $\\Rightarrow \\widehat{DAC}=45^o$ (2) <br\/> T\u1eeb (1) v\u00e0 (2) suy ra $\\widehat{ABC} = \\widehat{ACB} = \\widehat{CAD} (= 45^{o}) \\Rightarrow $ A \u0111\u00fang. <br\/> Tam gi\u00e1c $ACD$ vu\u00f4ng t\u1ea1i C, c\u00f3 $\\widehat{CDA} = 45^{o} $ <br\/> $\\Rightarrow \\widehat{CAD} = 45^{o} $ <br\/> $\\Rightarrow \\widehat{BAD} = 90^{o} + 45^{o} = 135^{o} \\Rightarrow $ B \u0111\u00fang. <br\/> C\u00f3 $\\widehat{BAC}= \\widehat{ACD} (= 90^{o}) \\Rightarrow AB \/\/ CD$ (so le trong) <br\/> C\u00f3 $\\widehat{CAD}= \\widehat{ACB} (= 45^{o}) \\Rightarrow AD \/\/ BC$ (so le trong) <br\/> $ \\Rightarrow $ C \u0111\u00fang <br\/> Tam gi\u00e1c ACD vu\u00f4ng c\u00e2n t\u1ea1i C n\u00ean: <br\/> $CA = CD = 1cm $ (v\u00ec AC = AB = 1cm) <br\/> $AD^{2} = AC^{2} + CD^{2} = 1^{2} + 1^{1} = 2 \\\\ \\Rightarrow AD = \\sqrt{2} $ <br\/> $\\Rightarrow $ D sai. <br\/> <br\/> <span class='basic_pink'> C\u00e2u tr\u1ea3 l\u1eddi sai l\u00e0 D. <\/span> ","column":2}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:23:02"},{"id":"1722","post_id":"998","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"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":[[["20"],["21"]]],"list":[{"point":10,"width":20,"content":"","type_input":"","ques":" <span class='basic_left'> Cho tam gi\u00e1c nh\u1ecdn $ABC$.<br\/> <center><img src='img\/H7B14-10.png' \/><\/center> <br\/> K\u1ebb $AH$ vu\u00f4ng g\u00f3c v\u1edbi $BC$ $(H \\in BC)$. <br\/> Cho bi\u1ebft $AB = 13cm, AH = 12cm, HC = 16cm$. <br\/> T\u00ednh \u0111\u1ed9 d\u00e0i c\u00e1c c\u1ea1nh $AC; BC$. <br\/> <b> \u0110\u00e1p \u00e1n: <\/b> $AC = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (cm) \\\\ BC = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (cm)$ ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> - D\u1ef1a v\u00e0o tam gi\u00e1c vu\u00f4ng $AHC$ t\u00ednh \u0111\u1ed9 d\u00e0i c\u1ea1nh $AC$. <br\/> - D\u1ef1a v\u00e0o tam gi\u00e1c vu\u00f4ng $AHB$ t\u00ednh \u0111\u1ed9 d\u00e0i c\u1ea1nh $BH$. <br\/> - T\u00ednh $BC = BH + HC$ <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <center><img src='img\/H7B14-10.png' \/><\/center>$\\triangle AHC $ vu\u00f4ng t\u1ea1i H n\u00ean theo \u0111\u1ecbnh l\u00ed Py-ta-go ta c\u00f3: <br\/> $AC^{2}$$ = AH^{2} + HC^{2} \\\\ = 12^{2} + 16^{2} \\\\ = 144 + 256 \\\\ = 400 = 20^{2} $ <br\/> $\\Rightarrow AC = 20 (cm) $ <br\/> $\\triangle AHB $ vu\u00f4ng t\u1ea1i B n\u00ean: <br\/> $BH^{2} $$= AB^{2} - AH^{2} \\\\ = 13^{2} - 12^{2} \\\\ = 169 - 144 \\\\ = 25 = 5^{2} $ <br\/> $\\Rightarrow BH = 5(cm) $ <br\/> Suy ra $BC = BH + HC = 5 + 16 = 21$ (cm) <\/span> <br\/> <br\/> <span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 20 v\u00e0 21 <\/span>"}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:23:02"},{"id":"1723","post_id":"998","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["100"]]],"list":[{"point":10,"width":20,"content":"","type_input":"","ques":"<span class='basic_left'>Cho tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i A, bi\u1ebft $AB = 8cm, BC = 17cm.$ <br\/> Tr\u00ean n\u1eeda m\u1eb7t ph\u1eb3ng b\u1edd $AC$ kh\u00f4ng ch\u1ee9a \u0111i\u1ec3m $B$, v\u1ebd tia $CD \\perp AC $ v\u00e0 $CD = 36cm.$ <br\/> T\u00ednh t\u1ed5ng \u0111\u1ed9 d\u00e0i c\u00e1c \u0111o\u1ea1n th\u1eb3ng $AB + BC + CD + DA$ <br\/> \u0110\u00e1p \u00e1n: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}(cm)$ <\/span> ","hint":"T\u00ednh $AC, AD$","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> T\u00ednh c\u1ea1nh AC. <br\/> <b> B\u01b0\u1edbc 2: <\/b> T\u00ednh AD. <br\/> <b> B\u01b0\u1edbc 3: <\/b> T\u00ednh t\u1ed5ng \u0111\u1ed9 d\u00e0i: $ AB + BC + CD + DA$ <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> <center><img src='img\/H7B14-40.png' \/><\/center> Tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i A n\u00ean theo \u0111\u1ecbnh l\u00ed Py-ta-go ta c\u00f3: <br\/> $BC^2=AB^2+AC^2$ <br\/> $AC^{2}$$ = BC^{2} - AB^{2} \\\\ = 17^{2} - 8^{2} \\\\ = 289 - 64 \\\\ = 225 = 15^{2} $ <br\/> $\\Rightarrow AC = 15(cm) $ <br\/> Tam gi\u00e1c ACD vu\u00f4ng t\u1ea1i C n\u00ean theo \u0111\u1ecbnh l\u00ed Py-ta-go ta c\u00f3: <br\/> $AD^{2}$$ = AC^{2} + CD^{2} \\\\ = 15^{2} + 36^{2} \\\\ = 1521 $<br\/> $\\Rightarrow BC = \\sqrt{1521} = 39 (cm) $ <br\/> Suy ra: $AB + BC + CD + DA$$ = 8 + 17 + 36 + 39 = 100$ (cm) <br\/><br\/> <span class='basic_pink'> V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0: 100 <\/span>"}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:23:02"}]}