pressure angle.
13-10 For a spur gearset with $\phi = 20^{\circ}$, while avoiding interference, find:
(a) The smallest pinion tooth count that will run with itself
(b) The smallest pinion tooth count at a ratio $m_G = 2.5$, and the largest gear tooth
count possible with this pinion
(c) The smallest pinion that will run with a rack
Repeat Problem 13-10 for a helic