cosa=0.3 sin^4A-COS^4a=?_数学解答

cosa=0.3 sin^4A-COS^4a=?

人气：233 ℃　时间：2020-05-24 20:46:06

解答

sin^4A-COS^4A
=(sin^2+cos^2A)(sin^2-cos^2A)
=sin^2A-cos^2A
=1-2cos^2A……………………因为cosA=0.3
=1-2×0.09
-1-0.18
=0.82