Term Picture Definition Notation

Classify by angle measure: Acute Angle An angle whose measure is less than 90°

Two angles that share a common vertex and Adjacent angles side, but have no

common interior points.

A figure formed by two Angle rays with a common

endpoint.

Angle bisector A ray that divides an angle into two angles that are congruent

When three points are Between collinear, then one

point is between the other two.

The set of all points in Circle a plane at a fixed

distance from a fixed point.

Collinear Points Points that lie on the

same line

Congruent Line segments that ̅̅ ̅̅̅ ̅̅ ̅̅̅ ̅ segments have the same length

Complementary Two angles whose measures have the sum 90°

Coplanar Points that lie in the same plane ( )

Distance along a J The length of a line JL=12 12 segment L Distance around The length of part of an arc the circumference of a ̂ circle

Equal lengths Congruent segments have the same AB=TO measure.

The set of points that ̅̅̅ ̅ two or more geometric Intersection figures have in common. ⋂

An undefined Line geometric term that has one dimension. It ⃡ extends without end in two directions. A portion of a line that consists of a defined Line Segment beginning and ̅̅̅ ̅ endpoint and all the points in between

Two adjacent angles Linear Pair whose noncommon sides are opposite rays

̅̅̅ ̅ ̅̅̅ ̅ Midpoint A point that bisects a segment into two or

congruent segments.

Classify by angle measure: An angles whose Obtuse Angle measure is greater than 90°

two rays with a ⃡ Opposite rays common endpoint that means “combined

form a line with”

A line that is a constant Parallel line distance from another ⃡ ⃡ line or plane

Perpendicular A line that intersects a line, a line segment, lines/segments ̅̅̅ ̅̅ ̅̅̅̅ ̅ ray or plane to form a right angle

An undefined term Point that has no dimensions. It is A usually represented by a dot ⃡ ̅̅̅ ̅ The point where two

Point of Intersection lines or segments meet. ⋂

An undefined term Plane that has two dimensions. It extends

without end in both dimensions Part of a line that consists of a point Ray called an endpoint and

all points on the line that extend in one direction

Classify by angle measure:

Right angle An angle with measure

equal to 90°

A point, ray, line, ̅̅̅ ̅ so Segment bisector segment, or plane that that ̅̅̅ ̅ ̅ ̅̅ ̅ intersects a segment at its midpoint. ⋂

Classify by angle measure: An angle with measure Straight angle equal to 180°

Supplementary Two angles whose angles measures have the

sum 180°

Vertical angles Two angle whose sides form two pairs of opposite rays