$2\mathrm{.}36$ A gate having the cross section shown in Fig. P$2\mathrm{.}36$ closes an opening $5ft$ wide and $4ft$ high in a water reservoir. The gate weighs $400lb$ and its center of gravity is $1ft$ to the left of $AC$ and $2ft$ above $BC.$ Determine the horizontal reaction that is developed on the gate at $C.$

FIGURE P$2\mathrm{.}36$