sin2α=2sinαcosα sin2{\alpha} = 2 sin\alpha cos\alpha

    cos2α=cos2α−sin2α=2cos2α−1=1−2sin2α cos2\alpha = cos^2\alpha - sin^2\alpha = 2cos^2\alpha - 1 = 1 - 2sin^2\alpha

    tan2α=2tanα1−tan2α tan2\alpha = \frac{2tan\alpha}{1-tan^2\alpha}