Given that
5cosθ−12sinθ≡Rcos(θ+α) 5 \cos \theta - 12 \sin \theta \equiv R \cos(\theta + \alpha) 5cosθ−12sinθ≡Rcos(θ+α)find the value of RRR, where R>0R > 0R>0.
Circle the correct answer from the options below:
555 \qquad 777 \qquad 131313 \qquad 171717
317 exam-style questions on AQA A Level Maths 1.8 E: Trigonometry, covering 1.8.1 Trigonometric definitions, rules and radians, 1.8.2 Small angle approximations (A-level only), 1.8.3 Trigonometric functions and exact values, 1.8.4 Reciprocal and inverse trigonometric functions (A-level only), 1.8.5 Trigonometric identities, 1.8.6 Compound and double angle formulae (A-level only), 1.8.7 Solving trigonometric equations, 1.8.8 Proofs with trigonometric identities, and 1.8.9 Trigonometry in context. Each one has a worked solution and a mark scheme showing where the marks go.