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Conjecture

A conclusion you reach using inductive reasoning.

Counterexample

Example for which conjecture is incorrect.

Point

A location. Has no size. Named by a capital letter.

Line

Series of points that extend in two opposite directions without end. Named by any two points on the line.

Collinear points

Points that lie on the same line.

Plane

Flat surface with no thickness.

Coplanar

Points and lines in the same plane.

Postulate

Accepted statement or fact.

Segment

Part of a line consisting of two endpoints and all points in between.

Ray

Part of a line consisting of one endpoint and all the points on the line on one side of the endpoint.

Opposite rays

Two collinear rays with the same endpoint.

Parallel lines

Coplanar lines that do not intersect

Skew lines

Lines that are noncoplanar

Midpoint

Halfway between the two endpoints of a segment

Equidistant

A point that is the same distance from two or more points.

Concurrent

Three or more lines all passing through the same point.

Perpendicular Lines

Two lines that intersect to form right angles.

Perpendicular Bisector

Line, segment, or ray that is perpendicular to the segment at its midpoint.

Angle Bisector

Ray that divides an angle into two congruent coplanar angles. Endpoint is the angle bisector.

Theorem

The statement that you prove true.