若 x = y,则 sin x = sin y "的逆否命题为真命题

求证sin²x-sin²y=sin(x+y)sin(x-y) 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 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| 已知tanx=x,tany=y,且|x|≠|y|,则sin(x+y)/(x+y)-sin(x-y)/(x-y)= y=(sin x + COS x)^2 求导 y=sin(x^x) y=sin(x)+x单调性 若2sin^2x+sin^2y=3sinx,则sin^2x+sin^2y的取值范围是 若sin（x+y）=1/2,sin（x-y）=1/3,则tanx/tany等于? 若 x = y,则 sin x = sin y 的逆否命题为真命题 已知sinx=1/3,sin(x+y)=1,则sin（2y+x)= sin(x*x+y)=xy 求y'x 已知sin(x+y)=1/3,sin(x-y)=1/5,则tanx/tany y=[sin^2(x)]*[sin^2(x)]求导 已知某质点运动学方程为x=10cos(πt),y=10sin(πt),（SI单位）