一道高数计算题（1/cos^2(x+y)）*（1+y')=y'怎么算到答案是y'=-1/sin^2(x+y)

Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y) y=cos(x-2),y=1+sin"pai"x为什么是周期函数,怎么算其周期 证明COS（X+Y）COS（X-Y）=COS^2X-SIN^2Y ∫（ e^x sin y- y )dx + (e^x cos y - 1)dy,是（2,0）的半圆周y=√2x-x^2 Matlab编程问题 cos(x*y)*cos(x*(1-y))-0.5x*sin(x*y)*sin(x*(1-y))= sin(x+y)-sinx=2cos(x+1/2y）sin(1/2y)的详细证明步骤. 求导y=(1+sin^2 x)/(cos(x^2)) sin(x+y)sin(x-y)=k,求cos^2x-cos^2y y=cos（-x）求导 1）y=cos（-x）=cos x y'=-sin x 2）y'=-sin（-x）= sin x 求证sin^2x+sin^2y-sin^2x*sin^2y+cos^2x*cos^2y=1 数学求导函数已知方程y=sin(x+y)确定了y是x的函数y=y(x),求d(y)对y求导的y=cos(x+y)(1+y y =(cos^2) x - sin (3^x),求y'