A Right Triangle Is Submerged Vertically with One Side at the Surface

Multiple Choice

A right triangle is submerged vertically with one side at the surface in a liquid of density $\rho$ . The triangle has a leg that is 9 m long located at the surface and a leg 9 m long straight down. Find the force exerted on the triangular surface, in terms of the density. Neglect the effect of the atmosphere above the liquid.

A) 243 $\rho$ N
B) 364.5 $\rho$ N
C) 121.5 $\rho$ N
D) 91.12 $\rho$ N
E) 20.25 $\rho$ N