If \(\alpha\) is the angle of blade tip at outlet, then maximum hydraulic efficiency of an impulse turbine is:

(a) \(\frac{1+\cos \alpha}{2}\)

(b) \(\frac{1-\cos \alpha}{2}\)

(c) \(\frac{1+\tan \alpha}{2}\)

(d) \(\frac{1-\tan \alpha}{2}\)