3sin^2 x+cos^2 x=2-cos2x怎么来的三角函数公式过程

已知sin(x)+3cos(x)=2,求sin(x)-cos(x)/sin(x)+cos(x)=? 2sin^2x - 5sin x cos x=3 cos^2x,求X, 化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x) 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x sin^3 x -cos^3 x sin^3 x -cos^3 x =(sin x -cos x )(sin^2 x +sin x*cos x +cos^2 x )问下这个是个公式还是什么?怎么样算出来的? y=2cos x (sin x+cos x) sin(x/2)cos(x/2)= sin[cos^2(x^3+x)],求导 y=(sin x + COS x)^2 已知:tan x=2 求:sin x+cos x/sin x-cos x=? 求证(3-sin^4 x-cos^4 x)/2cos^2 x=1+tan^2 x+sin^2 x Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y) 关于sin^2x+cos^2x 的应用式子：cos^6x+sin^6x=（cos^2x+sin^2x)(cos^4x-cos^2xsin^x+sin^4x)=(cos^2x+sin^2x)^2-3sin^2xcos^2x 求这两步算法中的具体思路 ps:cos^2x=cosx的二次方 sin^2 x-cos^2 x=cos 化简 1/2cos x-根号3/2sin x 根3sin x+cos x 怎么证明2(1-sin x)(1+cos x)=(1-sin x+cos x)^2 证明sin^4x-cos^4x=sin^2x-cos^2x