A triangular-based pyramid is a convex solid figure with a base in the shape of a triangle and triangular sides that meet at points called vertices, according to New South Wales Board of Studies. Convex means that all its interior angles are less than or equal to 180 degrees.
A triangular-based pyramid has exactly four faces, any of which can serve as the pyramid’s base. It also has six edges and four vertices. Other common pyramids include square-based pyramids and hexagonal-based pyramids. To find the surface area of a pyramid, add the areas of all its faces. To determine its volume, multiply the base times the perpendicular height, then divide the resulting product by three.