Eight sided figures: Octagon, regular polygon (8 sided)
A pyramid is a four-sided, three-dimensional figure.
A three sided figure with all unequal sides is called a scalene triangle. ■
it is a triangle.
a 3 sided figure
Diagonals connect corners of a figure. If you try to connect two corners of a three sided figure, the lines you draw will exactly mimic the sides of the figure. Because of this, a three sided figure has no diagonals.
A nine sided plane figure is a nonagon. A nine sided three dimensional figure is a nonahedron.
There cannot be a solid three sided figure. A solid 4 sided object is a tetrahedron.
triangle
triangle ?
A three dimensional figure with polygonal faces is called a polyhedron. Specific names draw from the Latin prefixes. For example a four sided figure is a tetrahedron.
A triangle
If it's three dimensional, a 12 sided figure is a dodecahedron.