Basics of Geometry Flashcards

A complete set of vocabulary flashcards covering the basics of geometry, including points, lines, planes, segments, and angle relationships based on the provided lecture notes.

Undefined Terms

Terms that are accepted without definition.

Point

A location in space represented by a dot.

Line

A straight path that extends infinitely in both directions.

Plane

A flat surface that extends infinitely in all directions.

Collinear Points

Points that lie on the same line.

Coplanar Points

Points that lie in the same plane.

Defined Terms

Terms that can be described using previously defined terms.

Line Segment

A part of a line with two endpoints.

Endpoints

The points at the ends of a line segment.

Ray

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

Opposite Rays

Two rays that share the same endpoint and form a line.

Intersection

The point or set of points where two lines, segments, or other figures meet.

Postulate

A statement that is accepted without proof.

Axiom

A statement that is accepted without proof.

Coordinate

A real number that corresponds to a point on a number line.

Distance Between Two Points

The absolute value of the difference between their coordinates.

Congruent Segments

Segments that have the same length.

Between

A point is between two other points if all three points are collinear and the point lies between them.

Midpoint

A point that divides a segment into two congruent segments.

Segment Bisector

A line, ray, segment, or plane that intersects a segment at its midpoint.

Acute Angle

An angle less than $90^{\circ}$.

Right Angle

An angle equal to $90^{\circ}$.

Obtuse Angle

An angle greater than $90^{\circ}$ but less than $180^{\circ}$.

Straight Angle

An angle equal to $180^{\circ}$.

Angle

A figure formed by two rays with a common endpoint.

Vertex

The common endpoint of the two rays that form an angle.

Sides of an Angle

The two rays that form an angle.

Interior of an Angle

The points between the sides of an angle.

Exterior of an Angle

The points outside the sides of an angle.

Measure of an Angle

The number of degrees contained in an angle.

Congruent Angles

Angles that have the same measure.

Angle Bisector

A ray that divides an angle into two congruent angles.

Adjacent Angles

Two angles that share a common vertex and a common side but have no common interior points.

Complementary Angles

Two angles whose measures have a sum of $90^{\circ}$.

Supplementary Angles

Two angles whose measures have a sum of $180^{\circ}$.