求证sin^2x+sin^2y-sin^2x*sin^2y+cos^2x*cos^2y=1

发布时间：2021-02-19 20:36:29

求证sin^2x+sin^2y-sin^2x*sin^2y+cos^2x*cos^2y=1

网友回答

sin^2x+sin^2y-sin^2x*sin^2y+cos^2x*cos^2y
= sin^2x-sin^2x*sin^2y+sin^2y+cos^2x*cos^2y
= sin^2x*(1-sin^2y)+sin^2y+cos^2x*cos^2y
= sin^2x*cos^2y+sin^2y+cos^2x*cos^2y
= sin^2x*cos^2y+cos^2x*cos^2y+sin^2y
= cos^2y(sin^2x+cos^2x)+sin^2y
= cos^2y *1 + sin^2y
= cos^2y + sin^2y
= 1
以上问题属网友观点，不代表本站立场，仅供参考！