1+sin2x+cos2x=1+sin(2x+π/4),

问题描述:

1+sin2x+cos2x=1+sin(2x+π/4),
为什么?

1+sin2x+cos2x
=1+√2(sin2x*√2/2+cos2x*√2/2)
=1+√2(sin2xcosπ/4+cos2xsinπ/4)
=1+√2sin(2x+π/4)