(cos^x+sin^2x)乘(cos^2x-sin^2x)=?

cos4x吗?
2024-12-28 09:58:30
推荐回答(2个)
回答1:

原式=1×cos2x
=cos2x

回答2:

cos^2 x+sin^2 x = 1
(cos^2 x+sin^2 x)(cos^2 x-sin^2 x) = cos^2 x - sin^2 x = cos2x