Knowing that a force $\mathbf{P}$ of magnitude $750 \mathrm{N}$ is applied to the pedal shown, determine (a) the diameter of the pin at $C$ for which the average shearing stress in the pin is $40 \mathrm{MPa}$, ( $b$ ) the corresponding bearing stress in the pedal at $C,(c)$ the corresponding bearing stress in each support bracket at $C$