化简y=sin(x+20度)+sin(x+80度

化简y=sin(x+20度)+sin(x+80度 matlab画y=sin(x)+sin(2*x)+...+sin(20*x)的图像 已知y=3sin(x+20)+5sin(x+80)求最小值 y=sin(2x+30度)求导,y'=? 证明sin(x+y)sin(x-y)=sinx-siny 化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x) 证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+ 化简sin(2x-y)*sin y+cos(2x-y)*sin y 设X属于（0,90度）,求y=[2sin^2(X)+1]/[sin(2X)]的最小值 sin(x)^y求导 sin(x.y)中, 一道三角恒等式证明题请证明sin(x+y)sin(x-y)=sin^2(x)-sin^2(y)