Hence, using secθsecθ−cosθ≡csc2θ\displaystyle \frac{\sec \theta}{\sec \theta - \cos \theta} \equiv \csc^2 \thetasecθ−cosθsecθ≡csc2θ, solve, for 0<θ<2π0 < \theta < 2\pi0<θ<2π, secθsecθ−cosθ=4cotθ\displaystyle \frac{\sec \theta}{\sec \theta - \cos \theta} = 4 \cot \thetasecθ−cosθsecθ=4cotθ
274 exam-style questions on Edexcel A Level Maths Trigonometric Functions, covering 6.1 Secant, Cosecant and Cotangent, 6.2 Graphs of Sec x, Cosec x and Cot x, 6.3 Using Sec x, Cosec x and Cot x, 6.4 Trigonometric Identities, and 6.5 Inverse Trigonometric Functions. Each one has a worked solution and a mark scheme showing where the marks go.