$2)$ A horizontal $\backslash (200-\backslash$mathrm$\{$N$\}\backslash )$ force is applied to the sloping member BCD$,$ whose bottom rests on a smooth horizontal plane. Its upper end is pinned at $\backslash ($ B $\backslash )$ to the horizontal member $\backslash ($ A B $\backslash ).$ What couple $\backslash ($ M $\backslash )$ must be applied to the member $\backslash ($ A B $\backslash )$ to hold the system in equilibrium? What is the magnitude of the pin reaction at $\backslash ($ B $\backslash )?$