Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

(i)[3]

Show that the equation $$\frac{\cos \theta - 4}{\sin \theta} - \frac{4 \sin \theta}{5 \cos \theta - 2} = 0$$ may be rewritten as $$9 \cos^2 \theta - 22 \cos \theta + 4 = 0.$$

(ii)[3]

Hence solve the equation $$\frac{\cos \theta - 4}{\sin \theta} - \frac{4 \sin \theta}{5 \cos \theta - 2} = 0$$ for $0^\circ \leq \theta \leq 360^\circ$.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: Set up the equation leading to $(\cos\theta-4)(5\cos\theta-2)-4\sin^2\theta=0$ (from the numerator)

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