Pythagorean trigonometric identity

Common card · No. 436541

The Pythagorean trigonometric identity, also called simply the Pythagorean identity, is an identity expressing the Pythagorean theorem in terms of trigonometric functions. Along with the sum-of-angles formulae, it is one of the basic relations between the sine and cosine functions. The identity is sin 2 ⁡ θ + cos 2 ⁡ θ = 1 {\displaystyle \sin ^{2}\theta +\cos ^{2}\theta =1} , where sin 2 ⁡ θ {\displaystyle \sin ^{2}\theta } means ( sin ⁡ θ ) 2 {\textstyle (\sin \theta )^{2}} and cos...

Read on Wikipedia