In geometry, a pyramid is a polyhedron formed by connecting a polygonal base and a point, called the apex.
Right angle
In geometry and trigonometry, a right angle is an angle that bisects the angle formed by two adjacent parts of a straight line.
Square
(For other uses, see Square (disambiguation).) In geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or right angles).
Triangle
A triangle is a polygon with three edges and three vertices.
Hyperboloid
In mathematics, a hyperboloid is a quadric in three dimensions described by the equation (hyperboloid of one sheet or hyperbolic hyperboloid), or (hyperboloid of two sheets or elliptic hyperboloid).
Solid angle
In geometry, a solid angle (symbol: Ω) is the two-dimensional angle in three-dimensional space that an object subtends at a point.
Dihedral angle
A dihedral angle is the angle between two intersecting planes.
Unit square
In mathematics, a unit square is a square whose sides have length 1.
Triquetra
(Not to be confused with Triquetrum (disambiguation).) Triquetra (/traɪˈkwɛtrə/; Latin tri- "three" and quetrus "cornered") originally meant "triangle" and was used to refer to various three-cornered shapes.
Spherical lune
In spherical geometry, a spherical lune is an area on a sphere bounded by two half great circles which meet at antipodal points, and is an example of a digon, {2}θ, with dihedral angle θ.
Lune (geometry)
In plane geometry, a lune is the concave-convex area bounded by two circular arcs, while a convex-convex area is termed a lens.