Show that the equation
2sin2x=4cos2x−cosx 2\sin^2 x = 4\cos^2 x - \cos x 2sin2x=4cos2x−cosxcan be expressed in the form
6cos2x−cosx−2=0 6\cos^2 x - \cos x - 2 = 0 6cos2x−cosx−2=0Hence, solve the equation
2sin22θ=4cos22θ−cos2θ 2\sin^2 2\theta = 4\cos^2 2\theta - \cos 2\theta 2sin22θ=4cos22θ−cos2θgiving all values of θ \theta\,θ between 0∘ 0^\circ\,0∘ and 180∘180^\circ180∘, correct to 1 decimal place.
Practise Edexcel A Level Maths Trigonometric Identities and Equations with exam-style questions for A Level Maths. 29 questions covering 10.1 Angles in all four Quadrants, 10.2 Exact Values of Trigonometric Ratios, 10.3 Trigonometric Identities, 10.4 Solving Trigonometric Equations, 10.5 Harder Trigonometric Equations, and 10.6 Equations and Identities, 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.
