Show that
cos3x≡4cos3x−3cosx \cos 3x \equiv 4\cos^3 x - 3\cos x cos3x≡4cos3x−3cosxHence find, using algebraic integration,
∫0π6cos3x dx \int_{0}^{\frac{\pi}{6}} \cos^3 x \, dx ∫06πcos3xdx31 exam-style questions on Edexcel A Level Maths 11.3 Using Trigonometric Identities. Each one has a worked solution and a mark scheme showing where the marks go.