Which of the following is equal to ?

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

Problem

Which of the following is equal to

\sin\theta\cos 18^{\circ}+\cos\theta\sin 18^{\circ}

? (a) \cos(\theta+18^{\circ}) (b) \cos(\theta-72^{\circ}) (c) \sin(\theta+18^{\circ}) (d) \sin(\theta-18^{\circ})