(a)[4]
Show that the expression $\dfrac{\cos 3x}{\sin x} + \dfrac{\sin 3x}{\cos x}$ is equal to $2\cot 2x$.
(b)[3]
Hence solve the equation $\dfrac{\cos 3x}{\sin x} + \dfrac{\sin 3x}{\cos x} = 4$, for $0 < x < \pi$.
Mathematics 9709 · AS & A Level · Trigonometry