A Level

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

Problem

\cos 5\theta=a\cos\theta+b\cos^3\theta+c\cos^5\theta+d

, then (1)

a=20

(2)

b=-30

(3)

a+b+c=2

(4)

a+b+c+d=1