Show that the equation 10cosθ=3cosecθ10 \cos \theta = 3 \operatorname{cosec} \theta10cosθ=3cosecθ can be written in the form sin2θ=k\sin 2\theta = ksin2θ=k where kkk is a constant to be found.
Hence find the smallest positive solution of the equation 10cosθ=3cosecθ10 \cos \theta = 3 \operatorname{cosec} \theta10cosθ=3cosecθ giving your answer, in degrees, to one decimal place.
Practise Edexcel A Level Maths 7.2 Double Angle Formulae with exam-style questions for A Level Maths. 24 questions, 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.