Trigonometry

Trigonometry on this paper goes beyond right-angled triangles to identities and equations.

The rules

For any triangle (sides $a, b, c$ opposite angles $A, B, C$): $$\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} \qquad a^2 = b^2 + c^2 - 2bc\cos A \qquad \text{Area} = \tfrac12 ab\sin C$$