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Prove that the identity $\frac{\cot x - \tan x}{\cot x + \tan x} = \cos 2x$ holds.
Mathematics 9709 · AS & A Level · Trigonometry
Trigonometry — practice question
Worked solution & mark scheme
This 3-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Express the LHS in terms of either $\cos x$ and $\sin x$ or $\tan x$.” …
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