sin2θ+cos2θ=1\sin^2\theta + \cos^2\theta = 1sin2θ+cos2θ=1; 1+tan2θ=sec2θ1 + \tan^2\theta = \sec^2\theta1+tan2θ=sec2θ; 1+cot2θ=csc2θ1 + \cot^2\theta = \csc^2\theta1+cot2θ=csc2θ.