Example $3(15$ points$)$

Problem $4\mathrm{.}15$ The magnitudes of the forces exerted

the pillar at $D$ by the cables $A,B,$ and $C$ are equal: $F_A$

$F_B=F_C.$ The magnitude of the total moment about

due to the forces exerted by the three cables at $D$

$1350kN-m.$ What is $F_A?$

Example $4(15$ points$)$

Problem $4\mathrm{.}58$ The rope exerts a force of magnitude

$|F|=200lb$ on the top of the pole at $B.$ Determine the

magnitude of the moment of $F$ about $A.$