A vertical force P $=10$ kips acts downward at vertex B of the ABC frame, as shown in Figure P$1\mathrm{.}4-19.$ The frame is supported by a frictionless pin in C and rests on a roller support in A$.($a$)$ Determine the reactions in A and C$,$ and $($b$)$ determine the internal results $($axial force, shear force, and bending moment$)$ in arbitrary cross$-$sections of the legs AB and BC$,$ using the respective notations shown in the two cuts.