Geometry Defined Terms

If three or more points all belong to the same line they are said to be collinear

If three or more lines contain the same point, they are said to be concurrent

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

Points B and C are said to be on the same side of point A if A, B, C are collinear and point A is not between point B and C.

A line segment is a set of two points and all the points between them.

A Ray is a set of points consisting of a fixed point of a line and all the points of the line on the same side of the fixed point.

Opposite Rays are two rays of the same line that have a common endpoint and no other point in common.

An angle is a set of points consisting of the union of 2 rays with a common endpoint (vertex)

A point P lies in the interior of an angle if there exist two points, one on each ray, neither at the vertex, such that the point P is between said two points.

Congruent Line Segments are line segments that are equal in measure

Congruent Angles are angles that are equal in measure

The midpoint of a line segment is a point of the line segment such that 2 segments formed are congruent.

A line segment bisector is a line that intersects the line segment at its midpoint.

A right angle is an angle measuring 90 degrees.

An acute angle is an angle measuring less than 90 degrees but greater than 0 degrees

An obtuse angle is an angle measuring greater than 90 degrees but less than 180 degrees

Complementary Angles are 2 angles the sum of whose measures is 90 degrees.

Supplementary Angles are 2 angles the sum of whose measuring 180 degrees

Two lines are said to intersect of they have a point in common

Perpendicular Lines are 2 lines that intersect and forms a right angle

An angle bisector is a ray whose endpoint is the vertex of the angle and that forms 2 congruent angles

A point of the line segment that forms 2 congruent segments is the midpoint of the line segment

A line that intersects the midpoint of a line segment is a line segment bisector

A angle whose measure is 90 degrees is a right angle

A ray whose endpoint is the vertex of the angle and that forms two congruent angles is an angle bisector.

Angles that are equal in measure are congruent

Line segments that are equal in measure are congruent

Adjacent angles are two angles in the same plane that share a common vertex and a common ray but share no other points.

Angles that form a linear pair are 2 adjacent angles such that their non-common rays are mutually opposite.