Topic 1 - Geometry Vocabulary

Point

A location, has no size

Line

Infinite number of points on a straight path, extends forever in two directions

Segment

Part of a line, has two endpoints

Ray

Part of a line, has one endpoint and a side that continues forever

Plane

Infinite number of points and lines on a flat surface, continues forever

Segment Measure

Length of the segment

Congruent

Two objects are congruent if they have the same size and shape, two segments are congruent if they have the same length

Midpoint

Divides the segment into two congruent segments

Segment Addition Postulate

Part + part = whole

Collinear

A set of 3 or more points that are ALL on the same line

Non-Collinear

A set of 3 or more points that are NOT all on the same line

Betweeness

B is between A and C if all 3 points are collinear and AB + BC = AC

Angle

The space between 2 intersecting lines/rays

Congruent Angles (≅)

Equal measurement

Acute Angle

Measure is LESS than 90°

Obtuse Angle

Measure is GREATER than 90°

Right Angle

Measure equals 90°

Straight Angle

Measure equals 180°

Adjacent

Two angles that share a vertex and a side

Linear Pair

Two adjacent angles that form a line (straight angle)

Vertical

A pair of opposite angles formed by two intersecting lines *they are congruent*

Complementary

Two angles that sum to 90° *do not have to be adjacent*

Supplementary

Two angles that sum to 180° *do not have to be adjacent*

Perpendicular Segments/Lines (⊥)

Two lines/segments that intersect and form a right angle

Angle Bisector

If a ray bisects an angle, it divides the angle into 2 *are congruent*