Question

若cos(π/6-α)=(根号3)/3,,,,求cos(5π/6+α)-sin^2(α-π/6)

麻烦写下过程,,,,事后+50

Answer 1

cos(5π/6+α)-sin^2(α-π/6) =cos[π-(π/6+α)]-1+cos^2(α-π/6)=-cos(π/6-α)-1+cos^2(π/6-α)
=-√3/3-1+1/3=-(2+√3)/3