Penjumlahan dan Perkalian Trigonometri

\(\sin 2x = 2 \sin x \cos x  \)

\(\cos 2x = \cos^2 x - \sin^2 x \)

\(\cos 2x = 2\cos^2 x - 1 \)

\(\cos 2x = 1 - 2\sin^2 x \)

\(\tan 2x = \dfrac{2 \tan x}{1 - \tan^2 x} \)

\(\sin 3x = 3 \sin x - 4 \sin^3 x  \)

\(\cos 3x = 4\cos^3 x - 3 \cos x \)

\(\tan 3x = \dfrac{3 \tan x - \tan^3 x}{1 - 3 \tan^2 x}\)

\(\cos^2 x = \frac{1}{2} + \frac{1}{2} \cos 2x \)

\(\sin^2 x = \frac{1}{2} - \frac{1}{2} \cos 2x \)