In case the number of teeth on two bevel gears in mesh is 30 and 60 respectively, then the pitch cone angle of the gear will be

(a) tan^-12

(b) п/2 + tan^-12

(c) п/2 – tan^-10.5

(d) tan^-10.5

I got this question in an online quiz.

This intriguing question comes from Standard Spur Gears-1 topic in portion Toothed Gearing & Gear Trains of Machine Kinematics