Forces P1 = 1500 lb and P2 = 2500 lb are applied at joint C of plane truss ABC shown in the figure part (a). Member AC has thickness tAC = 5/16 in. and member AB is composed of two bars each having thickness tAB / 2 = 3/16 in. [see figure part (b)]. Ignore the effect of the two plates which make up the pin support at A.
If the allowable shear stress in the pin is 12,000 psi and the allowable bearing stress in the pin is 20,000 psi, what is the minimum required diameter dmin of the pin?

dl AC AC AB AB Pin 2 support plats A Pin Section a-a