Which of the following formulae is used to determine minimum number of teeth required on helical pinion to avoid interference?

a. (2ha cos3 Ψ) / (mn sin2 Φn)

b. (mn zp / 2 cos Ψn)(1+G)

c. 1.15 π mn / sin Ψn

d. None of the above

ANSWER: (2ha cos3 Ψ) / (mn sin2 Φn)