(a)[3]
Show that the equation $\frac{4\cos\theta}{\tan\theta} + 15 = 0$ may be rewritten as $4\sin^2\theta - 15\sin\theta - 4 = 0$.
(b)[3]
Hence solve the equation $\frac{4\cos\theta}{\tan\theta} + 15 = 0$ for $0^\circ \leq \theta \leq 360^\circ$.
Mathematics 9709 · AS & A Level · Trigonometry
Trigonometry — practice question
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Rearrange $4\cos^2\theta+15\sin\theta=0$ by using $\tan\theta$ or the $\sin,\cos$ identities” …
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