Lines and Angles Lecture Notes

This set of vocabulary flashcards covers basic geometrical definitions related to lines, rays, segments, and angle properties as presented in the lecture notes.

Line

A collection of points going endlessly in both directions along a straight path, denoted as $AB$ when passing through points $A$ and $B$.

Line segment

A part of a line that has two end-points, denoted by $AB$ where $A$ and $B$ are the endpoints.

Ray

A part of a line that begins from one initial or starting point and travels endlessly in the direction specified by another point on it, denoted as $AB$ with $A$ as the initial point.

Point of intersection

A point, such as point $O$, that is present on both line segments ($AB$ and $PQ$) where they cross one another.

Vertex

The shared point, such as point $O$ in $\angle AOQ$, where the arms of an angle meet.

Arms

Also known as legs or sides of an angle, these are the rays or segments that form the angle, such as $OA$ and $OQ$ in $\angle AOQ$.

Interior of the angle

The region containing any point, such as point $X$, that lies between the two arms of an angle.

Exterior of the angle

The region containing any point, such as point $Z$, which is not between the two arms of an angle and is not on the boundary of the angle.

Magnitude

The opening between the two arms of an angle or the turn an arm must take to be in line with the other arm, expressed in degrees.

Degree

The unit of measurement used to express the magnitude of an angle.

Acute Angle

A type of angle identified during review as having a magnitude less than a right angle.

Obtuse Angle

A type of angle identified during review as having a magnitude greater than a right angle but less than a straight angle.

Right Angle

An angle that represents a 90-degree turn, often visually identified by a square corner.

Straight Angle

An angle that forms a straight line, representing a 180-degree turn.