The cross section of glass prism has the form of an isosceles triangle . One of equal face is silvered. A ray of light incident normally on other equal face and after being reflected twice, emerges through base of prism along normal. That the angle of prism is :-

Question

$(a)\;30^{\circ} \\ (b)\;36^{\circ} \\ (c)\;52^{\circ} \\ (d)\;60^{\circ}$