Let \( f(x) = 4\cos^{3}x + 3\sqrt{3}\cos^{2}x - 10 \). The number of points of local maxima of \( f \) in interval \( (0,\, 2\pi) \) is:
\( 1 \)
\( 4 \)
\( 2 \)
\( 3 \)