CAIE P3 2016 June — Question 5

Exam BoardCAIE
ModuleP3 (Pure Mathematics 3)
Year2016
SessionJune
TopicAddition & Double Angle Formulae

5
  1. Prove the identity \(\cos 4 \theta - 4 \cos 2 \theta \equiv 8 \sin ^ { 4 } \theta - 3\).
  2. Hence solve the equation $$\cos 4 \theta = 4 \cos 2 \theta + 3$$ for \(0 ^ { \circ } \leqslant \theta \leqslant 360 ^ { \circ }\).