Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

(a)[3]

Write $5\sin\theta + 12\cos\theta$ as $R\cos(\theta - \alpha)$, with $R > 0$ and $0 < \alpha < \frac{1}{2}\pi$.

(b)[4]

Hence solve for $x$ in the equation $5\sin 2x + 12\cos 2x = 6$ for $0 \leq x \leq \pi$.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Give $R=13$.” …