If the fundamental period of is

MATHEMATICS · Multi correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

If the fundamental period of

f(x)=\sin x+\cos\left(\sqrt{4-a^2}\,x\right)

4\pi

, then the value(s) of

a

is/are (1)

\frac{\sqrt{15}}{2}

(2)

-\frac{\sqrt{15}}{2}

(3)

\frac{\sqrt7}{2}

(4)

-\frac{\sqrt7}{2}