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
Practise Edexcel A Level Maths Trigonometry and Modelling with exam-style questions for A Level Maths. 100 questions covering 7.1 Addition Formulae, 7.2 Double Angle Formulae, 7.3 Solving Trigonometric Equations, 7.4 Simplifying a cos x +- b sin x, 7.5 Proving Trigonometric Identities, and 7.6 Modelling with Trigonometric Functions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.