cos2x+sin2x=________(请说明理由!)

问题描述:

cos2x+sin2x=________
(请说明理由!)

sin2x+cos2x
=√2(√2/2*sin2x+√2/2cos2x)
=√2(sin2xcosπ/4+cos2xsinπ/4)
=√2sin(2x+π/4)