Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

(i)[3]

From $4\tan x + 3\cos x + \frac{1}{\cos x} = 0$, show, without using a calculator, that $\sin x = -\frac{2}{3}$.

(ii)[4]

Hence, with all working shown, solve $4\tan(2x - 20^\circ) + 3\cos(2x - 20^\circ) + \frac{1}{\cos(2x - 20^\circ)} = 0$ for $0^\circ \leq x \leq 180^\circ$.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Multiplies by $\cos x$ or by a common denominator in order to obtain an equation in $\sin x$

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