Given that $ABC$ is a triangle and $\tan \frac{A}{2} = \frac{1}{4}$, without using a calcul

Question

Given that $ABC$ is a triangle and $\tan \frac{A}{2} = \frac{1}{4}$, without using a calculator, find $\tan A$ $\sin (B + C)$ $\cos A$ $\cos (B + C)$

Accepted Answer

(i) 8/15; (ii) 15/17; (iii) 8/17; (iv) -15/17

Trigonometry - Compound and Double-Angle Identities