|cos x|=sin(3π/2-x),求角x的取值范围

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 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? 已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值第一题1/2cos x-√3/2sin x第二题√3sin x+cos x第三题√2[sin x-cos x]第四题√2cos x-√6sin x 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 化简sin(x+7π/4)+cos(x-3π/4）步骤我已经找到撒sin(x+7π/4)+cos(x-3π/4)=sin(x+2π-π/4)+cos(x-π+π/4)我问下这一步是在干嘛?=sin(x-π/4)+cos[-(π-x-π/4)]=sin(x-π/4)+cos(π-x-π/4)=sin(x-π/4)-cos(x+π/4)=sin(x-π/4)-cos(x+π/2- 为什么cos(2x-π/3)-sin(5π/6) =cos(2x-π/3)? cos (2x-π/3)=2sinπ/4 y=2cos x (sin x+cos x) f(x)=2sin^2(π/4+x)+根号3(sin^2x+cos^2x)f(x)=2sin^2(π/4+x)+根号3(sin^2x-cos^2x) 符号打错了 sin(x/2)cos(x/2)= sin[cos^2(x^3+x)],求导 y=(sin x + COS x)^2 求证(3-sin^4 x-cos^4 x)/2cos^2 x=1+tan^2 x+sin^2 x 已知函数f(x)=cos(2x-π/3)+sin(^2)x+cos(^2)x.求化简～ f(x) = cos(2x-π/3) + sin^2x - cos^2x的对称轴方程