Question

求值:sin^2α+sin^2β-sin^2α×sin^2β+cos^2α×cos^2β

要详细过程，谢谢

Answer 1

sin²α+sin²β-sin²α×sin²β+cos²α×cos²β
=sin²α-sin²α×sin²β+cos²α×cos²β+sin²β
=sin²α×(1-sin²β)+cos²α×cos²β+sin²β
=sin²α×cos²β+cos²α×cos²β+sin²β
=(sin²α+cos²α)×cos²β+sin²β
=cos²β+sin²β
=1