化简sin(x+y)sin(x-y)+cos(x+y)cos(x-y)除了展开,有简便算法么?

化简sin(2x-y)*sin y+cos(2x-y)*sin y sin(x.y)中, sin(x)^y求导 化简sin(x+y)sin(x-y)-cos(x+y)cos(x-y)的结果是? 化简sin(x+y)cos(x-y)+cos(x+y)sin(x-y) C语言求三角函数f(x,y,z)=sin(x)/(sin(x-y)*sin(x-z))+sin(y)/(sin(y-x)*sin(y-z))+sin(z)/(sin(z-x)*sin(z-y))代码#include #include double fun(double x,double y,double z){double a,b,c,sum;a=sin(x)/(sin(x-y)*sin(x-z));b=sin(y)/(sin(y-x)*sin(y-z));c 求证sin²x-sin²y=sin(x+y)sin(x-y) 化简sin (x+y)sin x +cos (x+y)cos x= Mathematica y''+ sin(x) y=x 证明sin(x+y)sin(x-y)=sinx-siny y=sin根号x y=sinx+sin|x| sin(x+y)的导数 化简sin(x+y)sinx+cos(x+y)cosx 化简sin(x+y)sinx+cos(x+y)cosx等于? 化简cos(x+y)sinx-sin(x+y)cosx sin(2x+y)/sinx-2cos(x+y) 化简 化简cos(x+y)sinx-sin(x+y)cosx