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问题: 化简两个不同角角的函数

Sin2A+sin2B-sin2A *sin2B+cos2A*cos2B (注"2"代表平方)

解答:

Sin2A+sin2B-sin2A *sin2B+cos2A*cos2B

sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B
=sin^2A*(1-sin^2B)+cos^2A*cos^2B+sin^2B
=sin^2A*cos^2B+cos^2A*cos^2B+sin^2B
=cos^2B*(sin^2A+cos^2A)+sin^2B
=cos^2B+sin^2B
=1