Prove the identities:
sec2x−1≡tan2x\sec^2x - 1 \equiv \tan^2xsec2x−1≡tan2x
(secx−cosx)secx≡tan2x(\sec x - \cos x)\sec x \equiv \tan^2x(secx−cosx)secx≡tan2x
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.