Geometry 1

A location with no size or shape

A location with no size or shape

Point

Made up of points with no thickness or width

Line

A measurable part of a line consisting of two endpoints

Line segment

A line that extends indefinitely in one direction

Ray

A flat surface made up of points and extends indefinitely in a direction

Plane

Points that lie on the same line

• Non-Collinear:points that don’t lie on the same line

Collinear

Points that lie on the same plane

• Non-Coplanar:points that don’t lie on the same plane

Coplanar

If two segments have the same length, then they are congruent

Congruent segments

If A,B and C are collinear points and B is between A and C then AB+BC=AC

Segment addition postulate

The formula used to find the distance between two points on a coordinate plane

Distance formula

The formula used to find the midpoint between two endpoints

Midpoint formula

A segment, line, plane that can intersect a segment at its midpoint

Segment bisector

A line segment with associated direction

Directed line segment

The “run” of a directed line segment

Horizontal component

The “rise” of a directed line segment

Vertical component

Two lines that intersect at a 90° angle (right angle)

Perpendicular

A line, segment, or ray perpendicular to a segment at its midpoint

Perpendicular bisector

Two lines that never intersect

Parallel lines

The intersection of two right at an endpoint

Angle

The common endpoint of an angle (where two rays/sides, intersect)

Vertex

An angle with a degree measure of 90°

Right angle

An angle with a degree measure less than 90°

Acute angle

An angle with a degree measure greater than 90°

Obtuse angle

An angle with a degree measure of 180°

Straight angle

Two angles that have the same measure are congruent

Congruent angles

Two angles that share a common side and vertex “next to” each other

Adjacent angles

<ABD and <DBC are adjacent, then <ABD+ <DBC=<ABC

Angle addition postulate

A line or ray that divides an angle into two equal parts

Angle bisector

Two angles directly across from each other on intersecting

Vertical angles

Two angles with measures that sum to 90°

• DO NOT have to be adjacent

Complementary angles

Two angles with measures that sum to 180°

• DO NOT have to be adjacent

Supplementary angle

Adjacent angles that are supplementary. Combine, they form a straight line

Linear pair