This is a hexagonal prism: Volume = Area of Base (hexagon) x Height: There are 6 equal equilateral triangles in a hexagone. The apothem (or altitude of each triangle) = side x (√3)/2 =12(√3)/2 = 6√3 Area of ONE equilateral triangle = (side x altitude)/2: Area of ONE equilateral triangle = (12 x 6√3)/2 = 36√3 ft² Area of the SIX equilateral triangles = 36√3 x 6 = 216√3 ft² VOLUME = BASE X HEIGHT = 216√3 x 15 = 3240√3 ft³