A frame is designed such that friction alone keeps it from falling. The members $AB$ and $AC$ of the frame each weigh $1lb$ and both are of uniform material and thickness. The weights of the pads at $B$ and $C,$ the pin connection at $A,$ and the cable that extends from A to the box are all negligible. The coefficients of static friction between the walls and the pads are $0\mathrm{.}4$ at $B$ and $0\mathrm{.}2$ at $C.$

a$.)$ Based on the dimensions shown, what are the minimum normal forces at $B$ and $C$ necessary to keep this frame from falling?

b$.)$ Determine the internal axial force, shear force, and bending moment at $D$ under the conditions described in part $($a$.).($You may assume the thickness of the member ADC is negligible.$)$