Geometry Vocab 1

Points

A dot that has no size or shape

Line

Made up of points and it has no width or height it also extends infinitely in both directions

Plane

A flat surface made up of points any three points make up a plane and it extends infinitely in all directions.

Ray

A part of a line that has a fixed starting point and extends infinitely in one direction.

line segment

A part of a line that has two endpoints and is finite in length.

angle

Formed by two rays sharing a common endpoint, called the vertex, that measure the amount of turn between them.

supplementary angles

Two angles that add up to 180 degrees.

Complementary Angles

Two angles that add up to 90 degrees.

Linear pair

A pair of adjacent angles formed when two lines intersect, whose angles sum to 180 degrees.

Perpendicular lines

Lines that intersect to form right angles.

Midpoint of a segment

The point that divides a line segment into two equal parts, located exactly halfway between the segment's endpoints.

Mid point formula

A formula used to determine the midpoint between two points in a coordinate plane, calculated as ( (x1 + x2)/2, (y1 + y2)/2 ).

Distance formula

A formula used to calculate the distance between two points in a coordinate plane, expressed as √((x2 - x1)² + (y2 - y1)²).

Collinear

Points that lie on the same straight line.

Noncollinear

Points that do not lie on the same straight line.

Bisector

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

Right Angle

An angle that measures exactly 90 degrees.

acute angle

An angle that measures less than 90 degrees.

obtuse angle

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

straight angle

An angle that measures exactly 180 degrees.

straight angle

An angle formed by two rays that point in opposite directions, creating a line. It measures exactly 180 degrees.

parrallel lines

Lines that are always the same distance apart and never intersect.

Segment addition postulate

The length of a segment can be found by adding the lengths of its parts. If point B is between points A and C, then AB + BC = AC.

Angle addition postulate

The measure of an angle is equal to the sum of the measures of its adjacent angles. If point D is on the interior of angle ABC, then m∠ABD + m∠DBC = m∠ABC.