15% N2=75. Gear 5 has a module of 4.0 mm with N5=50.N4=40. All gears have pressure
angle of 20\deg , please determine
(a) pitch circle diameter of gear 4
(b) the center-to-center distance between gear 2 and gear 3
(c) N3=?
(d) base circle radius of gear 3
(e) Speed ratio of (\omega _(s))/(\omega _(2)) (注意轉動方向皆以 input 端觀測來定義)