Given that θ \theta\,θ is small,
use the small angle approximation of cosθ \cos \theta\,cosθ to show that
6cos(θ)+cos2(2θ)≈7−7θ2+4θ4 6 \cos (\theta) + \cos^2 (2\theta) \approx 7 - 7\theta^2 + 4\theta^4 6cos(θ)+cos2(2θ)≈7−7θ2+4θ4278 exam-style questions on Edexcel A Level Maths Radians, covering 5.1 Radian Measure, 5.2 Arc Length, 5.3 Areas of Sectors and Segments, 5.4 Solving Trigonometric Equations, and 5.5 Small Angle Approximations. Each one has a worked solution and a mark scheme showing where the marks go.