证明 sin^2A+sin^2B-sin^2Asin^2B+cos^2Acos^2

分类: 作业答案 • 2021-12-28 10:42:37

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

答

Sin^2A+Sin^2B-Sin^2ASin^2B+Cos^2ACos^2B
=Sin^2A(1-Sin^2B) + Sin^2B + Cos^2ACos^2B
=Sin^2ACos^2B+ Cos^2ACos^2B + Sin^2B
=Cos^2B+ Sin^2B
=1

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