Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

(i)[3]

On the same set of axes, sketch the graphs of $y = \sin x$ and $y = \cos 2x$ for $0^{\circ} \leq x \leq 180^{\circ}$.

(ii)[2]

Check that $x = 30^{\circ}$ is a root of the equation $\sin x = \cos 2x$, and give the other root of this equation for which $0^{\circ} \leq x \leq 180^{\circ}$.

(iii)[2]

Hence state the set of values of $x$, for $0^{\circ} \leq x \leq 180^{\circ}$, for which $\sin x < \cos 2x$.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Accurate graph of $y=\sin x$

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