Sheree drew this model of a tent. It is in the shape of a triangular prism with bases that are isoceles triangles. How many square inches of fabric are needed to make this model tent? A triangular prism. The triangular bases have a base of 8 inches, height of 3 inches, and side lengths of 5 inches. The height of the prism is 12 inches. 144 square inches 240 square inches 264 square inches 274 square inches.