For sinθ≠0\sin \theta \neq 0sinθ=0, prove that
cosec 2θ−cot2θ=tanθ \text{cosec } 2\theta - \cot 2\theta = \tan \theta cosec 2θ−cot2θ=tanθExplain why the identity cosec 2θ−cot2θ=tanθ\text{cosec } 2\theta - \cot 2\theta = \tan \thetacosec 2θ−cot2θ=tanθ is not valid when sinθ=0\sin \theta = 0sinθ=0.
137 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.