JUMLAH DAN SELISIH SUDUT
\(\sin (A + B) = \sin A \cos B + \cos A \sin B \)
\(\sin (A - B) = \sin A \cos B - \cos A \sin B \)
\(\cos (A + B) = \cos A \cos B - \sin A \sin B \)
\(\cos (A - B) = \cos A \cos B + \sin A \sin B \)
\(\tan (A + B) = \dfrac{\tan A + \tan B}{1 - \tan A \tan B} \)
\(\tan (A - B) = \dfrac{\tan A - \tan B}{1 + \tan A \tan B} \)
Sudut Rangkap
\(\sin 2x = 2 \sin x \cos x \)
\(\cos 2x = \cos^2 x - \sin^2 x \)
\(\cos 2x = 2\cos^2 x - 1 \)
\(\cos 2x = 1 - 2\sin^2 x \)
\(\tan 2x = \dfrac{2 \tan x}{1 - \tan^2 x} \)
\(\sin 3x = 3 \sin x - 4 \sin^3 x \)
\(\cos 3x = 4\cos^3 x - \cos x \)
\(\tan 3x = \dfrac{3 \tan x - \tan^3 x}{1 - 3 \tan^2 x}\)
\(\cos^2 x = \frac{1}{2} + \frac{1}{2} \cos 2x \)
\(\sin^2 x = \frac{1}{2} - \frac{1}{2} \cos 2x \)
PENJUMLAHAN DAN PERKALIAN
\(\sin A + \sin B = 2 \sin \frac{1}{2} (A + B) \cos \frac{1}{2} (A - B)\)
\(\sin A - \sin B = 2 \cos \frac{1}{2} (A + B) \sin \frac{1}{2} (A - B)\)
\(\cos A + \cos B = 2 \cos \frac{1}{2} (A + B) \cos \frac{1}{2} (A - B)\)
\(\cos A - \cos B = -2 \sin \frac{1}{2} (A + B) \sin \frac{1}{2} (A - B)\)
\(2 \sin A \cos B = \sin (A + B) + \sin (A - B) \)
\(2 \cos A \sin B = \sin (A + B) - \sin (A - B) \)
\(2 \cos A \cos B = \cos (A + B) + \cos (A - B) \)
\(-2 \sin A \sin B = \cos (A + B) - \cos (A - B) \)
RUMUS ALJABAR YANG SERING DIGUNAKAN
\((a + b)^2 = a^2 + 2ab + b^2\)
\((a - b)^2 = a^2 - 2ab + b^2\)
\(a^2 - b^2 = (a + b)(a - b)\)