Geometry with algebra

unit 1 definitions

Point

An exact location in space with no length, width, or thickness.

Line

A straight path with no endpoints that extends infinitely in both directions.

Plane

A flat surface that extends infinitely in all directions. named by a single lowercase letter or by three points on the plane that are not collinear.

Collinear

Points that lie on the same line.

Coplanar

Points or lines that lie in the same plane.

Notation

Symbols and letters used to name and represent geometric figures.

Reading Diagrams

Using labels, symbols, marks, and measurements in a diagram to determine geometric relationships.

Segment

A part of a line that has two endpoints.

Naming Segments / Notation

A segment is named by its two endpoints; the order does not matter.

Segment Length

The distance between the two endpoints of a segment.

Congruent Segments

Segments that have the same length.

Ray

A part of a line with one endpoint that extends infinitely in one direction.

Ray - Naming Ray / Notation

A ray is named using its endpoint first and another point on the ray second.

Opposite Ray

Two rays with the same endpoint that extend in opposite directions and form a line.

Segment Addition Postulate

If a point lies between two endpoints, the lengths of the two smaller segments add to equal the whole segment.

Segment Midpoint

A point that divides a segment into two congruent segments.

Segment Bisector

A line, ray, or segment that intersects a segment at its midpoint and divides it into two congruent parts.

Parts of an Angle

An angle has two sides, which are rays, and one common endpoint called the vertex.

Measure of an Angle

The amount of rotation between the sides of an angle, measured in degrees.

Adjacent Angles

Two angles that share a common vertex and one common side but do not overlap.

Congruent Angles

Angles that have the same measure.

Angle Bisector

A ray, segment, or line that divides an angle into two congruent angles.

Angle Addition Postulate

If a point lies inside an angle, the measures of the smaller adjacent angles add to equal the whole angle.

Acute Angle

An angle that measures more than 0° and less than 90°.

Right Angle

An angle that measures exactly 90°.

Obtuse Angle

An angle that measures more than 90° and less than 180°.

Straight Angle

An angle that measures exactly 180°.

Complementary Angles

Two angles whose measures add up to 90°.

Supplementary Angles

Two angles whose measures add up to 180°.

Linear Pair

Two adjacent angles whose noncommon sides form a straight line; their measures add to 180°.

Vertical Angles

Two opposite angles formed by intersecting lines; are congruent/equal

Angle Word Problems

Use angle relationships, definitions, and equations to find unknown angle measures.

Vertex

The common endpoint where two rays meet to form an angle.

Distance

The length between two points, usually measured along a segment.