Sine and Cosine rules (OCR GCSE Maths): Flashcards

Any triangle (not just right-angled)

Two angles and one side ($AAS$ or $ASA$)

Two sides and non-included angle ($SSA$)

$\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}$

$\frac{\sin A}{a} = \frac{\sin B}{b} = \frac{\sin C}{c}$

Lengths of the sides of the triangle

Angles opposite the sides $a$, $b$, $c$

When you have two sides and the included angle ($SAS$)

When you have all three side lengths ($SSS$)

$a^2 = b^2 + c^2 - 2bc \cos A$

$\cos A = \frac{b^2 + c^2 - a^2}{2bc}$

The angle between two given sides