It is given that
f(x)=3cosx−4sinxf(x) = 3\cos x - 4\sin xf(x)=3cosx−4sinx
and that f(x)=Rcos(x+α)f(x) = R\cos(x + \alpha)f(x)=Rcos(x+α), where R>0 R > 0\,R>0 and 0°≤α≤90°0° \leq \alpha \leq 90°0°≤α≤90°.
Find the value of R R\,R and the value of α\alphaα, giving α \alpha\,α to one decimal place.
Hence solve, for 0°≤x≤360°0° \leq x \leq 360°0°≤x≤360°, the equation
3cosx−4sinx=13\cos x - 4\sin x = 13cosx−4sinx=1
Give your answers to one decimal place.
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.