Given that y=sinθsinθ+kcosθ\displaystyle y = \frac{\sin \theta}{\sin \theta + k\cos \theta}y=sinθ+kcosθsinθ, where k k\,k is a non-zero constant
Show that dydθ=2k1+k2+(k2−1)cos2θ+2ksin2θ\displaystyle \frac{dy}{d\theta} = \frac{2k}{1+k^2+(k^2-1)\cos 2\theta+2k\sin 2\theta}dθdy=1+k2+(k2−1)cos2θ+2ksin2θ2k, giving your answer in exact form.
717 exam-style questions on Edexcel A Level Maths Differentiation, covering 9.1 Differentiating sin x and cos x, 9.2 Differentiating exponentials and logarithms, 9.3 The Chain Rule, 9.4 The Product Rule, 9.5 The Quotient Rule, 9.6 Differentiating Trigonometric Functions, 9.7 Parametric Differentiation, 9.8 Implicit Differentiation, 9.9 Using Second Derivatives, and 9.10 Rates of Change. Each one has a worked solution and a mark scheme showing where the marks go.