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Solve the equation $\cos \theta + 4\cos 2\theta = 3$, and give all of its solutions for $0^\circ \leq \theta \leq 180^\circ$.
Mathematics 9709 · AS & A Level · Trigonometry
Trigonometry — practice question
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply an appropriate trigonometric identity and form an equation in $\cos \theta$” …
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