Express 7cosx−4sinx7 \cos x - 4 \sin x7cosx−4sinx in the form Rcos(x+a)R \cos(x + a)Rcos(x+a) where R>0 R > 0\,R>0 and 0≤a≤π2\displaystyle 0 \leq a \leq \frac{\pi}{2}0≤a≤2π
Give full details of a sequence of two transformations needed to transform the curve
y=secx onto the curve y=17cosx−4sinx y = \sec x \text{ onto the curve } y = \frac{1}{7 \cos x - 4 \sin x} y=secx onto the curve y=7cosx−4sinx1137 exam-style questions on Edexcel A Level Maths Trigonometry and Modelling, 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. Each one has a worked solution and a mark scheme showing where the marks go.