(i)[3]
Show that the equation $\cos 2x(\tan^2 2x + 3) + 3 = 0$ may be rewritten as $2\cos^2 2x + 3\cos 2x + 1 = 0$.
(ii)[4]
Hence solve the equation $\cos 2x(\tan^2 2x + 3) + 3 = 0$ for $0^\circ \leq x \leq 180^\circ$.
Mathematics 9709 · AS & A Level · Trigonometry
Trigonometry — practice question
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct use of identities to rewrite $\tan^22x$ (for example $\tan^22x=\sec^22x-1$ or $\tfrac{\sin^22x}{\cos^22x}$).” …
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