f(x)=sin^2x+sinxcosx-1/2,化简
问题描述：
f(x)=sin^2x+sinxcosx-1/2,化简
答
(sinx-cosx)²/2
答
=2cosxsinx+sinxcosx-1/2=3sinxcosx-1/2
答
f(x)=(1-cos2x)/2+1/2*sin2x-1/2
=1/2(sin2x-cos2x)
=√2/2*(sin2x*√2/2-cos2x*√2/2)
=√2/2(sin2xcosπ/4-cos2xsinπ/4)
=√2/2sin(2x-π/4)