Mathematics

Problem

If the fundamental period of function

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

4\pi

, then the value of

a

is/are a.

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

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

\frac{\sqrt{7}}{2}

-\frac{\sqrt{7}}{2}