sinαcosα-2sin^2α=1/2sin2α-(1-cos2α)=1/2sin2α-1+cos2α=1/2sin2α+cos2α-1=1/2*2tanα/(1+tan^2α)+(1-tan^2α)/(1+tan^2α)-1=tanα/(1+tan^2α)+(1-tan^2α)/(1+tan^2α)-1=(1/2)/(1+1/4)+(1-1/4)/(1+1/4...