Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

(i)[3]

Express $(\sqrt{5})\cos\theta - 2\sin\theta$ in the form $R\cos(\theta + \alpha)$, with $R > 0$ and $0^\circ < \alpha < 90^\circ$. State the value of $\alpha$ correct to $2$ decimal places.

(ii(a))[4]

Hence solve the equation $(\sqrt{5})\cos\theta - 2\sin\theta = 0.9$ for $0^\circ < \theta < 360^\circ$.

(ii(b))[2]

State the maximum and minimum values of $10 + (\sqrt{5})\cos\theta - 2\sin\theta$ as $\theta$ changes.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: State or make clear $R=3$

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