Definitions

Term	Description
Ray	Directed line segment consisting of an endpoint and a direction. Notated as `\overrightarrow{EF}`, where `E` denotes the endpoint and `F` denotes a point along the ray.
Angle	Union of two rays with a common endpoint. Notated as `\angle DEF` or `\angle FED`, where `D` and `F` are along the points of each ray, and `E` is the vertex. `\angle EFD` is not valid notation, because the vertex must be the middle.
`\theta`	A lowercase theta is used to represent a (non right) angle in a triangle
`\phi`	A lowercase phi is used to represent another unknown angle in a triangle. As an example, in an algebraic equation, `x` might be used to represent the first unknown and `y` the second. In trig, `\theta` would