{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/1.jpg'\/><\/center>M\u1ed9t ng\u01b0\u1eddi nh\u00ecn v\u00e0o b\u1ec3 n\u01b0\u1edbc theo ph\u01b0\u01a1ng IM nh\u01b0 h\u00ecnh sau th\u00ec th\u1ea5y \u1ea3nh c\u1ee7a m\u1ed9t \u0111i\u1ec3m O ","select":["A. Tr\u00ean \u0111o\u1ea1n AN.","B. Tr\u00ean \u0111o\u1ea1n NH.","C. T\u1ea1i \u0111i\u1ec3m N.","D. T\u1ea1i \u0111i\u1ec3m H."],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec3m O c\u00f3 th\u1ec3 n\u1eb1m \u1edf tr\u00ean \u0111o\u1ea1n NH v\u00ec theo \u0111\u1ecbnh lu\u1eadt kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng th\u00ec khi \u00e1nh s\u00e1ng truy\u1ec1n t\u1eeb kh\u00f4ng kh\u00ed v\u00e0o n\u01b0\u1edbc th\u00ec g\u00f3c kh\u00fac xa lu\u00f4n nh\u1ecf h\u01a1n g\u00f3c t\u1eddi t\u1ee9c l\u00e0 \u0111i\u1ec3m O n\u1eb1m trong \u0111o\u1ea1n NH<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3591},{"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":"Quan s\u00e1t m\u1ed9t v\u1eadt nh\u1ecf qua m\u1ed9t k\u00ednh l\u00fap ta s\u1ebd th\u1ea5y: ","select":["A. M\u1ed9t \u1ea3nh c\u00f9ng chi\u1ec1u, nh\u1ecf h\u01a1n v\u1eadt.","B. M\u1ed9t \u1ea3nh c\u00f9ng chi\u1ec1u, l\u1edbn h\u01a1n v\u1eadt.","C. M\u1ed9t \u1ea3nh ng\u01b0\u1ee3c chi\u1ec1u, nh\u1ecf h\u01a1n v\u1eadt.","D. M\u1ed9t \u1ea3nh ng\u01b0\u1ee3c chi\u1ec1u, l\u1edbn h\u01a1n v\u1eadt."],"hint":"","explain":"<span class='basic_left'>K\u00ednh l\u00fap l\u00e0 m\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5 (h\u1ec7 th\u1ea5u k\u00ednh) c\u00f3 ti\u00eau c\u1ef1 ng\u1eafn <br\/>K\u00ednh l\u00fap l\u00e0 m\u1ed9t d\u1ee5ng c\u1ee5 h\u1ed5 tr\u1ee3 cho m\u1eaft \u0111\u1ec3 quan s\u00e1t v\u1eadt nh\u1ecf <br\/>S\u1ef1 t\u1ea1o \u1ea3nh c\u1ee7a K\u00ednh l\u00fap: V\u1eadt nh\u1ecf qua K\u00ednh l\u00fap cho \u1ea3nh \u1ea3o, l\u1edbn h\u01a1n v\u1eadt. m\u1eaft ta nh\u00ecn th\u1ea5y \u1ea3nh \u1ea3o n\u00e0y<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3592},{"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":"\u0110\u1eb7t m\u1ed9t v\u1eadt AB c\u00f3 d\u1ea1ng \u0111o\u1ea1n th\u1eb3ng nh\u1ecf, cao 2 cm, vu\u00f4ng g\u00f3c v\u1edbi tr\u1ee5c ch\u00ednh c\u1ee7a m\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5, c\u00e1ch th\u1ea5u k\u00ednh 5 cm. Th\u1ea5u k\u00ednh c\u00f3 ti\u00eau c\u1ef1 10 cm.<br\/> \u1ea2nh l\u00e0 \u1ea3nh th\u1eadt hay \u1ea3nh \u1ea3o? \u1ea2nh n\u1eb1m c\u00e1ch th\u1ea5u k\u00ednh bao nhi\u00eau xentimet? \u1ea2nh cao bao nhi\u00eau xentimet? ","select":["A. \u1ea2nh \u1ea3o, c\u00e1ch th\u1ea5u k\u00ednh 10cm, cao 4cm","B. \u1ea2nh \u1ea3o, c\u00e1ch th\u1ea5u k\u00ednh 10cm, cao 2cm","C. \u1ea2nh Th\u1eadt, c\u00e1ch th\u1ea5u k\u00ednh 10cm, cao 4cm","D. \u1ea2nh \u1ea3o, c\u00e1ch th\u1ea5u k\u00ednh 5cm, cao 4cm"],"hint":"","explain":"<span class='basic_left'>D\u1ef1ng \u1ea3nh c\u1ee7a v\u1eadt AB theo \u0111\u00fang t\u1ec9 l\u1ec7 nh\u01b0 h\u00ecnh sau. <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/3a.jpg'\/><\/center><br\/>\u1ea2nh \u1ea3o.v\u00ec \u0111\u1eb7t v\u1eadt n\u1eb1m trong kho\u1ea3ng ti\u00eau c\u1ef1<br\/>\u1ea2nh c\u00e1ch th\u1ea5u k\u00ednh 10 cm v\u00e0 cao 4 cm, ta th\u1ea5y hai tam gi\u00e1c ABO v\u00e0 A'B'O \u0111\u00f4ng d\u1ea1ng v\u1edbi nhau theo tr\u01b0\u1eddng h\u1ee3p g\u00f3c g\u00f3c, n\u00ean ta c\u00f3 t\u1ef7 l\u1ec7 $\\dfrac{AB}{A'B'}=\\dfrac{AO}{A'O}=\\dfrac{1}{2}$<br\/> suy ra A'B' = 2.AB= 4cm, OA' = OA = 10cm<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3593},{"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":"M\u1ed9t ng\u01b0\u1eddi quan s\u00e1t c\u00e1c v\u1eadt qua m\u1ed9t th\u1ea5u k\u00ednh ph\u00e2n k\u00ec, \u0111\u1eb7t c\u00e1ch m\u1eaft 10 cm th\u00ec th\u1ea5y \u1ea3nh c\u1ee7a m\u1ecdi v\u1eadt xa, g\u1ea7n \u0111\u1ec1u hi\u1ec7n l\u00ean c\u00e1ch m\u1eaft trong kh\u1ecfang 50 cm tr\u1edf l\u1ea1i. X\u00e1c \u0111\u1ecbnh ti\u00eau c\u1ef1 c\u1ee7a th\u1ea5u k\u00ednh ph\u00e2n k\u00ec. ","select":["A. 10 cm.","B. 20 cm.","C. 40 cm.","D. 30 cm."],"hint":"","explain":"<span class='basic_left'> V\u00ec \u1ea3nh c\u1ee7a t\u1ea5t c\u1ea3 c\u00e1c v\u1eadt n\u1eb1m tr\u01b0\u1edbc th\u1ea5u k\u00ednh ph\u00e2n k\u00ec \u0111\u1ec1u l\u00e0 \u1ea3nh \u1ea3o n\u1eb1m trong kh\u1ecfang t\u1eeb ti\u00eau \u0111i\u1ec3m \u0111\u1ebfn quang t\u00e2m c\u1ee7a th\u1ea5u k\u00ednh, n\u00ean ti\u00eau c\u1ef1 c\u1ee7a th\u1ea5u k\u00ednh ph\u00e2n k\u00ec n\u00e0y l\u00e0 50 cm \u2013 10 cm = 40 cm.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":3594},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/5.jpg'\/><\/center>Tr\u00ean h\u00ecnh d\u01b0\u1edbi \u0111\u00e2y c\u00f3 v\u1ebd m\u1ed9t tia s\u00e1ng chi\u1ebfu t\u1eeb kh\u00f4ng kh\u00ed v\u00e0o n\u01b0\u1edbC. \u0110\u01b0\u1eddng n\u00e0o trong s\u1ed1 c\u00e1c \u0111\u01b0\u1eddng 1, 2, 3, 4 c\u00f3 th\u1ec3 \u1ee9ng v\u1edbi tia kh\u00fac x\u1ea1? ","select":["A. \u0110\u01b0\u1eddng 1.","B. \u0110\u01b0\u1eddng 2.","C. \u0110\u01b0\u1eddng 3.","D. \u0110\u01b0\u1eddng 4."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":3595},{"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":"M\u1eaft c\u1eadn c\u00f3 nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m n\u00e0o d\u01b0\u1edbi \u0111\u00e2y? ","select":["A. \u0110i\u1ec3m c\u1ef1c c\u1eadn qu\u00e1 g\u1ea7n m\u1eaft. \u0110i\u1ec3m c\u1ef1c vi\u1ec5n qu\u00e1 xa m\u1eaft.","B. \u0110i\u1ec3m c\u1ef1c c\u1eadn qu\u00e1 xa m\u1eaft. \u0110i\u1ec3m c\u1ef1c vi\u1ec5n qu\u00e1 g\u1ea7n m\u1eaft.","C. \u0110i\u1ec3m c\u1ef1c c\u1eadn v\u00e0 \u0111i\u1ec3m c\u1ef1c vi\u1ec5n qu\u00e1 g\u1ea7n m\u1eaft.","D. \u0110i\u1ec3m c\u1ef1c c\u1eadn v\u00e0 \u0111i\u1ec3m c\u1ef1c vi\u1ec5n qu\u00e1 xa m\u1eaft."],"hint":"","explain":"<span class='basic_left'>M\u1eaft c\u1eadn c\u00f3 nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m l\u00e0: \u0110i\u1ec3m c\u1ef1c c\u1eadn v\u00e0 \u0111i\u1ec3m c\u1ef1c vi\u1ec5n qu\u00e1 g\u1ea7n m\u1eaft.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":1}]}],"id_ques":3596},{"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":"D\u00f9ng m\u00e1y \u1ea3nh \u0111\u1ec3 ch\u1ee5p \u1ea3nh m\u1ed9t v\u1eadt cao 80 cm, \u0111\u1eb7t c\u00e1ch m\u00e1y 2 m. Sau khi tr\u00e1ng phim th\u00ec th\u1ea5y \u1ea3nh cao 2 cm. H\u00e3y t\u00ednh kho\u1ea3ng c\u00e1ch t\u1eeb phim \u0111\u1ebfn v\u1eadt k\u00ednh l\u00fac ch\u1ee5p \u1ea3nh ","select":["A. 5cm","B. 10cm","C. 2cm","D. 8cm"],"hint":"","explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/7a.jpg'\/><\/center> Kho\u1ea3ng c\u00e1ch t\u1eeb phim \u0111\u1ebfn v\u1eadt k\u00ednh: <br\/>\u0394OA\u2019B\u2019 ~ \u0394OA'B' n\u00ean ta c\u00f3: $OA'=OA\\times \\dfrac{A'B'}{AB}=\\dfrac{200\\times 2}{8}=5$ cm<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3597},{"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":"D\u00f9ng m\u00e1y \u1ea3nh m\u00e0 v\u1eadt k\u00ednh c\u00f3 ti\u00eau c\u1ef1 5 cm \u0111\u1ec3 ch\u1ee5p \u1ea3nh m\u1ed9t ng\u01b0\u1eddi \u0111\u1ee9ng c\u00e1ch m\u00e1y 3 m. D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd, h\u00e3y x\u00e1c \u0111\u1ecbnh kh\u1ecfang c\u00e1ch t\u1eeb phim \u0111\u1ebfn v\u1eadt k\u00ednh l\u00fac ch\u1ee5p \u1ea3nh. ","select":["A. 4,08cm","B. 5,08cm","C. 6cm","D. 2cm"],"hint":"","explain":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/8a.jpg'\/><\/center>Kho\u1ea3ng c\u00e1ch t\u1eeb phim \u0111\u1ebfn v\u1eadt k\u00ednh: <br\/>\u0394FA\u2019B\u2019 ~ \u0394FOI n\u00ean ta c\u00f3: $FA'=FO\\times \\dfrac{A'B'}{OI}=\\dfrac{f\\times d'}{d}$ <br\/>Do \u0111\u00f3 kho\u1ea3ng c\u00e1ch t\u1eeb phim \u0111\u1ebfn v\u1eadt k\u00ednh l\u00e0: d\u2019 = OA\u2019 =OF + FA\u2019 = $f+\\dfrac{f\\times d'}{d}$ <br\/>Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh n\u00e0y ta \u0111\u01b0\u1ee3c: $d'=\\dfrac{d\\times f}{d-f}=\\dfrac{300\\times 5}{300-5}\\approx 5,08$ cm<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3598},{"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\u1ed9t h\u1ecdc sinh nh\u00ecn c\u1ed9t c\u1edd cao 9m. Mu\u1ed1n \u1ea3nh c\u1ee7a c\u1ed9t c\u1edd cao 1cm r\u00f5 n\u00e9t tr\u00ean v\u00f5ng m\u1ea1c v\u00e0 c\u00e1ch th\u1ec3 th\u1ee7y tinh 2cm th\u00ec h\u1ecdc sinh \u0111\u00f3 ph\u1ea3i \u0111\u1ee9ng c\u00e1ch c\u1ed9t c\u1edd m\u1ed9t kho\u1ea3ng ","select":["A. 18m.","B. 9m.","C. 4,5m.","D. 36m."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3599},{"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":"Khi nh\u00ecn m\u1ed9t v\u1eadt \u1edf c\u00e1ch m\u1eaft 10m th\u00ec \u1ea3nh c\u1ee7a v\u1eadt tr\u00ean m\u00e0ng l\u01b0\u1edbi c\u00f3 \u0111\u1ed9 cao 0,5cm. Bi\u1ebft kho\u1ea3ng c\u00e1ch t\u1eeb th\u1ec3 th\u1ee7y tinh \u0111\u1ebfn m\u00e0ng l\u01b0\u1edbi l\u00e0 2cm. \u0110\u1ed9 cao c\u1ee7a v\u1eadt s\u1ebd l\u00e0 ","select":["A. 5m.","B. 2,5m.","C. 15m.","D. 2m."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3600},{"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":"Khi nh\u00ecn m\u1ed9t t\u00f2a nh\u00e0 cao 10m \u1edf c\u00e1ch m\u1eaft 20m th\u00ec \u1ea3nh c\u1ee7a t\u00f2a nh\u00e0 tr\u00ean m\u00e0ng l\u01b0\u1edbi m\u1eaft c\u00f3 \u0111\u1ed9 cao bao nhi\u00eau? Bi\u1ebft kho\u1ea3ng c\u00e1ch t\u1eeb th\u1ec3 th\u1ee7y tinh \u0111\u1ebfn m\u00e0ng l\u01b0\u1edbi l\u00e0 2cm. ","select":["A. 0,5cm.","B. 1,0cm.","C. 1,5cm.","D. 2,0cm."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3601},{"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 ng\u01b0\u1eddi nh\u00ecn r\u00f5 m\u1ed9t v\u1eadt. Bi\u1ebft kho\u1ea3ng c\u00e1ch t\u1eeb th\u1ec3 th\u1ee7y tinh \u0111\u1ebfn m\u00e0ng l\u01b0\u1edbi c\u1ee7a m\u1eaft ng\u01b0\u1eddi \u0111\u00f3 l\u00e0 2cm. Kho\u1ea3ng c\u00e1ch t\u1eeb \u1ea3nh c\u1ee7a v\u1eadt \u0111\u00f3 \u0111\u1ebfn th\u1ec3 th\u1ee7y tinh cu\u0309a m\u0103\u0301t ","select":["A. b\u0103\u0300ng 0cm.","B. b\u0103\u0300ng 2cm.","C. b\u0103\u0300ng 5cm.","D. b\u1eb1ng v\u00f4 c\u00f9ng"],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3602},{"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\u0103\u0301t cu\u0309a ba\u0323n \u0110\u00f4ng co\u0301 khoa\u0309ng c\u01b0\u0323c c\u00e2\u0323n la\u0300 10cm. Bi\u1ebft kho\u1ea3ng c\u00e1ch t\u1eeb \u0111i\u1ec3m c\u1ef1c c\u1eadn \u0111\u1ebfn c\u1ef1c vi\u1ec5n l\u00e0 40cm. Ba\u0323n \u0110\u00f4ng kh\u00f4ng \u0111eo ki\u0301nh se\u0303 th\u00e2\u0301y v\u00e2\u0323t xa nh\u1ea5t c\u00e1ch m\u0103\u0301t ","select":["A. 50cm.","B. 40cm.","C. 30cm.","D. 400cm."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3603},{"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":"M\u1ed9t ng\u01b0\u1eddi quan s\u00e1t c\u00e1c v\u1eadt qua m\u1ed9t th\u1ea5u k\u00ednh ph\u00e2n k\u00ec, \u0111\u1eb7t c\u00e1ch m\u1eaft 10cm th\u00ec th\u1ea5y \u1ea3nh c\u1ee7a m\u1ecdi v\u1eadt xa, g\u1ea7n \u0111\u1ec1u hi\u1ec7n l\u00ean c\u00e1ch m\u1eaft trong kho\u1ea3ng 50cm tr\u1edf l\u1ea1i. Th\u1ea5u k\u00ednh ph\u00e2n k\u00ec m\u00e0 ng\u01b0\u1eddi \u0111\u00f3 \u0111ang \u0111eo c\u00f3 ti\u00eau c\u1ef1 ","select":["A. 10cm.","B. 50cm.","C. 40cm.","D. 60cm."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":3604},{"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":"\u0110\u1eb7t m\u1ed9t v\u1eadt s\u00e1ng AB cao 4cm c\u00e1ch th\u1ea5u k\u00ednh ph\u00e2n k\u1ef3 kho\u1ea3ng 40cm. Ta thu \u0111\u01b0\u1ee3c \u1ea3nh A'B' c\u00e1ch th\u1ea5u k\u00ednh 10cm t\u00ecm chi\u1ec1u cao c\u1ee7a \u1ea3nh A'B'? ","select":["A. 11cm","B. 1cm","C. 16cm","D. 2cm"],"hint":"","explain":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/15a.jpg'\/><\/center><span class='basic_left'>Ta th\u1ea5y :\u25b3ABO \u223c\u25b3A'B'O (g\u00f3c-c\u1ea1nh -g\u00f3c) <br\/>ta c\u00f3 t\u1ef7 l\u1ec7 $\\dfrac{AB}{A'B'}=\\dfrac{AO}{A'O'}$ <br\/>suy ra $A'B'=\\dfrac{AB\\times A'O}{AO}=\\dfrac{4\\times 10}{40}=1$ cm.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3605},{"time":24,"part":[{"title":"L","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"C\u00e2u tr\u1ea3 l\u1eddi n\u00e0o kh\u00f4ng \u0111\u00fang?<br\/> M\u1ed9t ng\u01b0\u1eddi d\u00f9ng k\u00ednh l\u00fap c\u00f3 ti\u00eau c\u1ef1 10cm \u0111\u1ec3 quan s\u00e1t m\u1ed9t v\u1eadt nh\u1ecf. V\u1eadt \u0111\u1eb7t c\u00e1ch k\u00ednh 5cm th\u00ec. ","select":["A. \u1ea2nh c\u00e1ch k\u00ednh 5cm.","B. \u1ea2nh qua k\u00ednh l\u00e0 \u1ea3nh \u1ea3o.","C. \u1ea2nh c\u00e1ch k\u00ednh 10cm.","D. \u1ea2nh c\u00f9ng chi\u1ec1u v\u1edbi v\u1eadt."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3606},{"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 k\u00ednh l\u00fap c\u00f3 ti\u00eau c\u1ef1 f = 12,5cm, \u0111\u1ed9 b\u1ed9i gi\u00e1c c\u1ee7a k\u00ednh l\u00fap \u0111\u00f3 l\u00e0: ","select":["A. G = 10.","B. G = 2.","C. G = 8.","D. G = 4."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3607},{"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\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5 c\u00f3 ti\u00eau c\u1ef1 f = 20cm. M\u1ed9t v\u1eadt th\u1eadt AB c\u00e1ch th\u1ea5u k\u00ednh 40cm. \u1ea2nh thu \u0111\u01b0\u1ee3c l\u00e0 ","select":["A. \u1ea3nh th\u1eadt, c\u00e1ch th\u1ea5u k\u00ednh 40cm, ng\u01b0\u1ee3c chi\u1ec1u v\u1eadt v\u00e0 \u0111\u1ed9 cao b\u1eb1ng v\u1eadt.","B. \u1ea3nh th\u1eadt, c\u00e1ch th\u1ea5u k\u00ednh 20cm, ng\u01b0\u1ee3c chi\u1ec1u v\u1eadt v\u00e0 \u0111\u1ed9 cao b\u1eb1ng v\u1eadt.","C. \u1ea3nh th\u1eadt, c\u00e1ch th\u1ea5u k\u00ednh 40cm, c\u00f9ng chi\u1ec1u v\u1eadt v\u00e0 \u0111\u1ed9 cao b\u1eb1ng v\u1eadt.","D. \u1ea3nh \u1ea3o, c\u00e1ch th\u1ea5u k\u00ednh 10cm, c\u00f9ng chi\u1ec1u v\u1eadt v\u00e0 l\u1edbn h\u01a1n v\u1eadt."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":1}]}],"id_ques":3608},{"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":"Tr\u00ean gi\u00e1 \u0111\u1ee1 c\u1ee7a m\u1ed9t th\u1ea5u k\u00ednh c\u00f3 ghi 2,5x. \u0110\u00f3 l\u00e0: ","select":["A. M\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5 c\u00f3 ti\u00eau c\u1ef1 2,5 cm.","B. M\u1ed9t th\u1ea5u k\u00ednh ph\u00e2n k\u00ec c\u00f3 ti\u00eau c\u1ef1 2,5 cm.","C. M\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5 c\u00f3 ti\u00eau c\u1ef1 10 cm.","D. M\u1ed9t th\u1ea5u k\u00ednh ph\u00e2n k\u00ec c\u00f3 ti\u00eau c\u1ef1 10 cm."],"hint":"","explain":"<span class='basic_left'>Do k\u00ednh l\u00fap l\u00e0 m\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5 <br\/>\u00c1p d\u1ee5ng h\u1ec7 th\u1ee9c: $G=\\dfrac{25}{f}$ n\u00ean ta c\u00f3 $f=\\dfrac{25}{G}=\\dfrac{25}{2,5}=10$ <br\/>N\u00ean ch\u1ecdn \u0111\u00e1p \u00e1n C M\u1ed9t th\u1ea5u k\u00ednh h\u1ed9i t\u1ee5 c\u00f3 ti\u00eau c\u1ef1 10 cm.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":3609},{"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":"\u0110\u1eb7t m\u1ed9t v\u1eadt s\u00e1ng AB cao 4cm tr\u01b0\u1edbc th\u1ea5u k\u00ednh ph\u00e2n k\u1ef3. Ta thu \u0111\u01b0\u1ee3c \u1ea3nh A'B' cao 2cm, c\u00e1ch th\u1ea5u k\u00ednh 10cm. V\u1eadt AB c\u00e1ch th\u1ea5u k\u00ednh bao nhi\u00eau? ","select":["A. 10cm","B. 20cm","C. 0,8cm","D. 0,5cm"],"hint":"","explain":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai51/lv2/img\/20a.jpg'\/><\/center><span class='basic_left'> \u25b3ABO \u223c \u25b3 A'B'O (g\u00f3c-c\u1ea1nh -g\u00f3c) <br\/>ta c\u00f3 t\u1ef7 l\u1ec7 $\\dfrac{AB}{A'B'}=\\dfrac{AO}{A'O}$ <br\/>suy ra $AO=\\dfrac{AB\\times A'O}{A'B'}=\\dfrac{4\\times 10}{2}=20$. cm. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3610}],"lesson":{"save":0,"level":2}}