Trigonify

Power Reduction

cos² θ

cos⁡2θ=1+cos⁡2θ2\cos^{2}\theta = \dfrac{1 + \cos 2\theta}{2}

Related Power Reduction identities

sin² θ

Study this and 44 more identities in the Trigonify workspace — an interactive unit circle, a step-by-step triangle solver, quizzes, and a practice problem bank.