Question $3$:

The water in a $25-m-$deep reservoir is kept inside by a $90-$m$-$wide wall whose cross section is an equilateral triangle, as shown in Fig. P$11-47.$ Determine $($a$)$ the total force $($hydrostatic $+$ atmospheric$)$ acting on the inner surface of the wall and its line of action, $($b$)$ the magnitude of the horizontal component of this force and $($c$)$ the distance of the pressure center from the free surface of water along the wall surface. Take $P_{\text{a}\text{t}\text{m}}=100$kPa. Answer $($a$)=3\mathrm{.}19{10}^{8}N$;$(b)=2\mathrm{.}76{10}^{8}N$;$(c)=17\mathrm{.}1m$