如何化简sin^2(-a-5π/2)-cos^2(a-7π/2)/{sin(a-3π/2)+cos(

发布时间：2021-02-19 20:48:27

如何化简sin^2(-a-5π/2)-cos^2(a-7π/2)/{sin(a-3π/2)+cos(-a-3π/2)}拜托了

网友回答

sin^2(-a-5π/2)-cos^2(a-7π/2)/{sin(a-3π/2)+cos(-a-3π/2)}
=[-sin(2π+a+π/2)]^2-cos^2(-4π+a+π/2)/{sin(-2π+a-π/2)+cos(2π+a-π/2)}
=[cos^2(a)-sin^2a]/{cosa+sina]
=cosa-sina
=√2sin(π/4-a)
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