# Q.The contact ratio is given by

• A(Length of the path of approach)/(Circular pitch)
• B(Length of path of recess)/(Circular pitch)
• C(Length of the arc of contact)/(Circular pitch)
• D(Length of the arc of approach)/cosφ

(Length of the arc of contact)/(Circular pitch)

Hints :

The contact ratio is given by (Length of the arc of contact)/(Circular pitch).

The lower pairs are _________ pairs

For an involute gear, the ratio of base circle radius and pitch circle radius is equal to