(a)[4]
Prove that the identity $\cot^2 \theta - \tan^2 \theta = 4 \cot 2\theta \cosec 2\theta$ holds.
(b)[4]
Hence solve the equation $\cot^2 x - \tan^2 x = 5\sec 2x$ for $0^\circ < x < 90^\circ$.
Mathematics 9709 · AS & A Level · Trigonometry
Trigonometry — practice question
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Rewrite the left-hand side in terms of $\sin\theta$ and $\cos\theta$” …
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