They are made of straight lines, all in one plane, such that pairs of them meet at vertices.
They are called polygons
A pyramid
All triangles are polygons, so you just call them triangles.
Because all other polygons are made from triangles as for example an 8 sided octagon has 6 triangles within it or a 6 sided hexagon has 4 triangles within it.
geodesic
Most triangles, quadrilaterals, and other polygons with five or more sides; most closed shapes with curved sides.Most triangles, quadrilaterals, and other polygons with five or more sides; most closed shapes with curved sides.Most triangles, quadrilaterals, and other polygons with five or more sides; most closed shapes with curved sides.Most triangles, quadrilaterals, and other polygons with five or more sides; most closed shapes with curved sides.
Quadrilaterals are polygons with four sides. Triangles are polygons with three sides.
A triangle forms other polygons as for instance there are 4 triangles in an hexagon and 8 triangles in a decagon
equilateral triangles and regular pentagons
Scalene triangles, rectangles, rhombi, concave polygons with 5 or more sides.
The polygons are the equilateral triangle, the square, and the regular pentagon. The faces of these platonic solids are made from the following polygons: tetrahedron - 4 triangles cube - 6 squares octahedron - 8 triangles dodecahedron - 12 pentagons icosahedron - 20 triangles
They are said to be regular polygons such as equilateral triangles, squares and other polygons that have congruent sides and equal congruent interior angles.