Angle -- from Wolfram MathWorld

Given two intersecting lines or line segments, the amount of rotation about the point of intersection (the vertex) required to bring one into correspondence with the other is called the angle theta between them. The term "plane angle" is sometimes used to distinguish angles in a plane from solid angles measured in space (International Standards Organization 1982, p. 5). The term "angle" can also be applied to the rotational offset between intersecting planes about their

Brocard Angle -- from Wolfram MathWorld

Modular Angle -- from Wolfram MathWorld

Line -- from Wolfram MathWorld, line

Circle - Wikipedia

Angles: Definition, Parts, Types, Degrees, Properties, Examples

Dihedral Angle -- from Wolfram MathWorld

What is the simplest-to-understand proof of the existence of the

Perpendicular Bisector Definition, Theorem & Examples - Lesson

Line-Line Angle -- from Wolfram MathWorld

CUDA for quaternions (hyper-complex numbers) operations - CUDA

Pentaflake, in Google SketchUp - 3DVinci