化简求值1/2*sin2α-cos^2(π/4-α)

问题描述:

化简求值1/2*sin2α-cos^2(π/4-α)

1/2*sin2α-cos^2(π/4-α)
=1/2*sin2α-[1+cos(π/2-2α)]/2
=1/2*sin2α-1/2-1/2*sin2α
=-1/2.