In solving the equation

MATHEMATICS · Single correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

In solving the equation sin⁡x+sin⁡3x=0\sin x + \sin 3x = 0, the left-hand side can first be rewritten as (a) 2cos⁡2xsin⁡x2 \cos 2x \sin x (b) 2sin⁡2xcos⁡x2 \sin 2x \cos x (c) 2sin⁡2xsin⁡x2 \sin 2x \sin x (d) 2cos⁡2xcos⁡x2 \cos 2x \cos x

Related theory

Browse the problem library