化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b

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化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b化简sin^2a+sin^2

化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b
化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b

化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b
sin²a+sin²b-sin²asin²b+cos²acos²b
=sin²a+sin²b(1-sin²a)+cos²acos²b
=sin²a+sin²bcos²a+cos²acos²b
=sin²a+cos²a(sin²b+cos²b)
=sin²a+cos²a
=1

sin^2a+sin^2b-sin^2a*sin^2a+cos^2a*cos^2b
=sin^2a(1-sin^2b)+sin^2b+cos^2a*cos^2b
=sin^2acos^2b+sin^2b+cos^2a*cos^2b
=cos^2b(sin^2a+cos^2a)+sin^2b
=cos^2b+sin^2b
=1