cosαsinβ=1/6,sin(α-β) = sinαcosβ - cosαsinβ = sinαcosβ - 1/6 = 1/3, sinαcosβ = 1/2sin(α+β) = sinαcosβ + cosαsinβ = 1/2 + 1/6 = 2/3cos(2α+2β) = cos2(α+β) = 1 - 2[sin(α+β)]^2 = 1 - 8/9 = 1/9
