text: what is the surface area of the prism if its base are right triangles with legs 3 meters and 4 meters? a triangular prism has of 12 meters. (s=ph+2b) your question isn't clear about the height of the prism; is the height 12 meters?  the base is a 3-4-5 right triangle (because 3^2 + 4^2 = 25, and sqrt(25) = 5), so the base perimeter is 3+4+5 = 12 meters, and the area of the base is 3*4/2 = 6 square meters.  assuming the height is 12 meters, the surface area is 12*12 + 2*6 = 156 square meters.