Problem $4$: A tripod is made from three $33\frac{1}{4}$ inch steel angles each $12$ ft long. In a plan view,

these angles are spaced $120$ degrees apart. Assuming that the ends of these angles are pin$-$ended,

what is magnitude of allowable vertical load, F$,$ that may be applied to tripod? Use Euler's

formula with a factor of safety $n=3.$