bai tap toan lop 12 co dap an

... π π 2016 2 126 ).2533( . 8 = + 0,5 điểm 2) (2 điểm) Ta có 3 1 (Cos 3A + Cos 3B) - 2 1 (Cos 2A + Cos 2B) + Cos A +CosB = 6 5 (1) ⇔ 3 1 (4 Cos 3 A - 3 CosA + 4 Cos 3 B - 3CosB) - 2 1 (2Cos 2 A-1+2Cos 2 B- 1)+CosA+CosB ... = 6 13 ã Vậy 6 13 coscoscos 1 coscoscos ++ +++ CBA CBA Dấu bằng xảy ra khi: CBA coscoscos ++ = 2 3 hay tam giác đều. 0.5 0.5 0.5 0.5 4 Tuyển tập các đề thi HSG Toán lớp 12 (có đáp án chi ... Suy ra βα α βα βα gg l gg OO IEggIEOO cotcot cos cotcot ' )cot(cot' + = + =⇔+= 0.5 điểm 0.5 điểm 12 Tuyển tập các đề thi HSG Toán lớp 12 (có ỏp ỏn chi tit) (phn 1) == 2 2 1 2 00 0 0 xx y x ã...

... 2 . Vậy tập nghiệm của phương trình là T= { } 3 1;log 2 0,25 0,25 0,25 0,25 3 Xét hs: 2 2 ( ) cos 1; 0, 2 f x x x x π   = + ữ Cm p ổ ử ữ ỗ > " ẻ ữ ỗ ữ ỗ ố ứ ' y 0 x 0; 2 ... Ox ỡ ù = ù ớ ù ù ợ ' 0 ó 2 nghiệm phân biệt y=0 ó 2 nghiệm phân biệt y c c 0,25 0,25 MÔN : TOÁN– LỚP 12 BÀI CÂU NỘI DUNG ĐIỂM I 1 Hàm số : y= x 3 +3x 2 +1 +TXĐ : D=R +Sự biến thiên : Giới hạn...

... 1 120 cos 4 ( )x t cm π = và 2 120 cos(4 )( ) 3 x t cm π π = − . Phương trình dao động tổng hợp là: A. 120 3 cos(4 )( ) 6 x t cm π π = + B. 120 3 cos(4 )( ) 3 x t cm π π = + C. 120 3 cos(4 ... vật là: A. 12cos 4 ( ) 3 x t cm π π   = −  ÷   B. 12cos ( ) 3 x t cm π π   = +  ÷  C. 12cos 4 ( ) 3 x t cm = + ữ D. 12cos 4 ( ) 6 x t cm = + ữ 133. Một con lắc lò ... 3 cos 100 3 t ữ (cm) v x 2 = 3cos 100 6 t + ữ (cm). Phng trỡnh dao động tổng hợp là : A. 3 2 cos(100 )( ) 12 x t cm π π = − B. 6cos(100 )( ) 12 x t cm π π = − C. 3 2 cos(100...

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... planet. Each time a species is lost, the complexity, natural balance, and beauty of our world is diminished. And what threatens plants and animals ultimately threatens people as well. 86. According ... planet. Each time a species is lost, the complexity, natural balance, and beauty of our world is diminished. And what threatens plants and animals ultimately threatens people as well. 36. According ... focuses on the conservation of three biomes that contain most of the world's biodiversity: forests, freshwater ecosystems, and oceans and coasts. Among other issues, it is also concerned (49)...

... are many forms of communication in existence today. B. Ideas and thoughts can be expressed by body language. C. Blind people can communicate with each other in Braille. D. Everyone can use an oral ... techniques also express human thoughts and feelings. However, they cannot replace verbal language completely. For instance, no matter how pictuesque and vivid sign language is, it cannot be used to express ... are many forms of communication in existence today. B. Ideas and thoughts can be expressed by body language. C. Blind people can communicate with each other in Braille. D. Everyone can use an oral...

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... 11 cos 12 π . b) Cho a 3 sin 4 = với a 0 0 90 180< < . Tính cosa, tana. c) Chứng minh: x x x 4 4 2 sin cos 1 2cos− = − . Câu 4: Cho tam giác ABC có AB = 3, AC = 4, BC = 5 . Tính cosB ... Đề số 12 ĐỀ ÔN TẬP HỌC KÌ 2 – Năm học Môn TOÁN Lớp 10 Thời gian làm bài 90 phút Câu 1: Giải các bất phương trình sau: a) x x 2 3...