2sin(x-π/4)sin(x+π/4)要怎么算?怎么得到(sinx－cosx)(sinx＋cosx)的?是把sin(x-π/4)和sin(x+π/4拆开算好再乘以2么?没有简便的方法么

sin(x+π/4) 2sin(x+π/4)sin(x-π/4)=? sin^2(π/4 +x) 求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2). f(x)=（1+cotx)sin^2x-2sin(x+π/4)sin(x-π/4)还有一题, 已知函数f(x)=(1+1 anx)sin^2x+m sin(x+π/4)sin(x-π/4) sin(x+π/4)sin(x-π/4)等于什么? 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2(π/3-x) 根号2sin(x+π/4)化简 sin（x+π）的奇偶性sin(x+π)的奇偶性sin(x+π/2)的奇偶性sin(x+π/4)的奇偶性 函数f(x)=2sin(x+π/4)sin(x-π/4)+sin2x的值域 求f【x】=2sin[x+π/4]sin[x-π/4]+sin2x的最大值 化简2sin^2[(π/4)+x]+根号3（sin^x-cos^x）-1 定积分0到π x*((sin(x))^2-(sin(x))^4)^(1/2) 化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x 傅里叶级数作图f（x）=2sin[x] - sin[2x] + 2/3sin[3x] - 1/2sin[4x]我用mathematica输入程序Plot[{2sin[x],-2sin[x],2sin[x] - sin[2x],-2sin[x] + sin[2x],2sin[x] - sin[2x] + 2/3sin[3x],-2sin[x] + sin[2x] - 2/3sin[3x],2sin[x] - sin[2x] + 2/3si 求sin^2(2x+π/3)的导数这样写为什么不对：[sin^2(2x+π/3)]'=[sin(2x+π/3)·sin(2x+π/3)]'=2[sin(2x+π/3)]'·sin(2x+π/3)=2cos(2x+π/3)·sin(2x+π/3)=sin(4x+2π/3)