the base of a triangular pyramid is triangle
If it is a pyramid, then the base shape is a SQURE. If it is a tetrahedron, then the base shape is a triangle.
It is a pyramid
A tetrahedron or triangular pyramid
No.
That would be a triangular pyramid.
Pyramids are classified by the shape of their base. A triangular pyramid has a triangular base and three triangular side faces. A square pyramid has a square base and four triangular sides. A pentagonal pyramid has a pentagonal base and five triangular sides. A hexagonalpyramid has a hexagonal base and six triangular sides, and so on.
The shape you are describing is a triangular pyramid. A triangular pyramid has a base that is a triangle and three triangular faces that meet at a single point called the apex. The base of the pyramid is a rectangle, which is a quadrilateral with four right angles. The triangular faces of the pyramid connect the vertices of the base to the apex.
If the base of the pyramid is a triangle then all its faces would be triangular in shape.
A 3-sided pyramid.
A pyramid perhaps
Triangular Pyramid