$(4)$ Two wires, $AB$ and $BC$ in Fig. $4,$ support a lamp weighing $18$ lb $.$ Wire $AB$ is at

an angle $=34$ to the horizontal and wire $BC$ is at an angle $=48.$ Both wires

have diameter $0\mathrm{.}03$ in $.$ Determine the tensile stresses ${}_{AB}$ and ${}_{BC}$ in two wires.

Figure $3$