化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b_数学解答

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

人气：457 ℃　时间：2020-01-29 21:06:57

解答

sin²a+sin²b-sin²asin²b+cos²acos²b
=sin²a+sin²b(1-sin²a)+cos²acos²b
=sin²a+sin²bcos²a+cos²acos²b
=sin²a+cos²a(sin²b+cos²b)
=sin²a+cos²a
=1