The difference between the greatest and least values of the function is

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

Problem

The difference between the greatest and least values of the function

f(x)=\cos x+\frac{1}{2}\cos2x-\frac{1}{3}\cos3x

is (1)

\frac{4}{3}

(2)

1

(3)

\frac{9}{4}

(4)

\frac{1}{6}