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Find the solutions of $\cos(x + 30^\circ) = 2\cos x$, with all answers taken from the interval $-180^\circ < x < 180^\circ$.
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 the $\cos(A+B)$ identity to produce an equation in $\cos x$ and $\sin x$” …
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