Trigonify

Topics · 3 identities

Double Angle

Rewriting functions of 2θ in terms of functions of θ.

sin 2θ

sin⁡2θ=2sin⁡θcos⁡θ\sin 2\theta = 2 \sin\theta \cos\theta
Open identity

cos 2θ

cos⁡2θ=cos⁡2θ−sin⁡2θ=2cos⁡2θ−1=1−2sin⁡2θ\cos 2\theta = \cos^{2}\theta - \sin^{2}\theta = 2\cos^{2}\theta - 1 = 1 - 2\sin^{2}\theta
Open identity

tan 2θ

tan⁡2θ=2tan⁡θ1−tan⁡2θ\tan 2\theta = \dfrac{2\tan\theta}{1 - \tan^{2}\theta}
Open identity