A square or quadrilateral.
a trapezuim
square
A triagular based pyramid has 4 corners, 6 edges and 4 faces
a quadrilateral
Ovals; circles; any circular shape with no edges or corners
a trapezuim
square
rectangle
A triagular based pyramid has 4 corners, 6 edges and 4 faces
A triagular based pyramid has 4 corners, 6 edges and 4 faces
a square of course
4
Rectangle with round corners
a quadrilateral
A triangular pyramid has 4 corners and 6 edges (and 4 faces).
A tetrahedron; a shape made of four triangles.
They are an interesting nice solid geometric shape with straight lines and pointy corners.