Prove that:
sin4α−cos4α≡1−2cos2α\sin^4 \alpha - \cos^4 \alpha \equiv 1 - 2\cos^2 \alphasin4α−cos4α≡1−2cos2α
Hence solve, for 0≤α≤3600 \leq \alpha \leq 3600≤α≤360, the equation,
sin4α−cos4α=0.5 \sin^4 \alpha - \cos^4 \alpha = 0.5 sin4α−cos4α=0.554 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.