A mechanical linkage is set at an obtuse angle ϕ\phiϕ. The equilibrium position of the linkage is determined by the equation
(4sinϕ+cosϕ)2+(2sinϕ−2cosϕ)2=10.4 (4 \sin \phi + \cos \phi)^2 + (2 \sin \phi - 2 \cos \phi)^2 = 10.4 (4sinϕ+cosϕ)2+(2sinϕ−2cosϕ)2=10.4Find the exact value of sinϕ\sin \phisinϕ. Fully justify your answer.
137 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.