Which following equation represents the frictional torque transmitted in a conical pivot bearing with radius R of shaft and $$\alpha$$ as the semi-angle of the cone?

A

$$\frac{1}{2} \times \mu.W.R \cosec \alpha$$

B

$$\frac{2}{3} \times \mu.W.R \cosec \alpha$$

C

$$\frac{3}{4} \times \mu.W.R \cosec \alpha$$

D

$$\mu.W.R \cosec \alpha$$