Prove the identities:
sec2x−cosec2x≡tan2x−cot2xsec^2x - \text{cosec}^2x \equiv \tan^2x - \cot^2xsec2x−cosec2x≡tan2x−cot2x
(ksecx−cosx)2≡k2tan2x−sin2x+(k−1)2(k\sec x - \cos x)^2 \equiv k^2\tan^2x - \sin^2x + (k-1)^2(ksecx−cosx)2≡k2tan2x−sin2x+(k−1)2
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.