A truss analysis includes consideration of Joint $\backslash ($ B $\backslash )$ as shown. If $\backslash ($ B x $\backslash )$ is $2\mathrm{.}9$ kips and $\backslash ($ B y $\backslash )$ is $9\mathrm{.}4$ kips, find member force $\backslash ($ A B $\backslash )$ in kips. Use positive for tension and negative for compression. The horizontal distance from A to B is $16$ ft $,$ the horizontal distance from B to C is $18$ feet, and the vertical distance from $\backslash ($ A $\backslash )$ to $\backslash ($ B $\backslash )$ and $\backslash ($ C $\backslash )$ is $12$ ft $.$