Use the identities for sin(A+B)\sin(A+B)sin(A+B), cos(A+B)\cos(A+B)cos(A+B) and tan(A+B)\tan(A+B)tan(A+B) to express sin2A \sin 2A\,sin2A in terms of sinA \sin A\,sinA and cosA\cos AcosA, cos2A \cos 2A\,cos2A in terms of sinA \sin A\,sinA and cosA \cos A\,cosA and hence in terms of (i) cosA \cos A\,cosA and (ii) sinA\sin AsinA, and tan2A \tan 2A\,tan2A in terms of tanA\tan AtanA.
348 exam-style questions on Edexcel A Level Maths Trigonometry and Modelling, covering 7.1 Addition Formulae, 7.2 Double Angle Formulae, 7.3 Solving Trigonometric Equations, 7.4 Simplifying a cos x +- b sin x, 7.5 Proving Trigonometric Identities, and 7.6 Modelling with Trigonometric Functions. Each one has a worked solution and a mark scheme showing where the marks go.