$2\mathrm{.}8\mathrm{.}21$ WP A homogeneous, $4-$ ft $-$wide, $8-$ ft $-$long rectangular gate weigh$-$

ing $800$ lb is held in place by a horizontal flexible cable as shown in Fig.

P$2\mathrm{.}8\mathrm{.}21.$ Water acts against the gate, which is hinged at point $A.$ Friction

in the hinge is negligible. Determine the tension in the cable.

FIGURE P$2\mathrm{.}8\mathrm{.}21$