证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1

问题描述:

证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2
证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1