A Tetrahedron has four triangular sides.
The only thing I can come up with would be a tetrahedron. You could make a pyramid with a square (open) base, I guess.
equilateral triangles and regular pentagons
It is a regular octahedron.
4.
square
rhombus
Tetrahedron.
yolo
A square pyramid.
It is a tetrahedron pyramid
What figure has 6 flat surfaces that all look exactly the same
Tetrahedron
A pyramid.
A tetrahedron
A pyramid with a triangular base. The faces are 4 equilateral triangles.
Pyramid. Work: 4 sides (that you usually see) are triangles, the base (bottom) is a square
A square-based pyramid