You may use the identity cos3x≡4cos3x−3cosx\cos 3x \equiv 4\cos^3 x - 3\cos xcos3x≡4cos3x−3cosx.
Solve, for −π≤x≤π-\pi \leq x \leq \pi−π≤x≤π, the equation
1−cos3x=sin2x1 - \cos 3x = \sin^2 x1−cos3x=sin2x
Give your answers to three significant figures where they are not exact.
225 exam-style questions on WJEC A Level Maths 3.5 Trigonometry (A-level only), covering 3.5.1 Trigonometry (A-level only), 3.5.2 Trigonometry (A-level only), 3.5.3 Trigonometry (A-level only), 3.5.4 Trigonometry (A-level only), 3.5.5 Trigonometry (A-level only), 3.5.6 Trigonometry (A-level only), 3.5.7 Trigonometry (A-level only), and 3.5.8 Trigonometry (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.