Geometry Chapter 1 Vocabulary

17 terms · First terms students need to know for basic geometry.

point

an exact location in space

line

made up of points and has no thickness or width

plane

A flat surface that extends without end in all directions

theorem

a true statement that follows as a result of other true statements

postulate

a statement that is accepted as true without proof

degree

A unit used to measure distances around a circle. One degree equals 1/360 of a full circle.

ray

A part of a line, with one endpoint, that continues without end in one direction

opposite rays

2 rays that have the same endpoint and go in opposite directions forming a line

angle

A figure formed by two rays with a common endpoint

sides

Two rays that make up an angle

vertex

The common endpoint of an angle

interior

Inside of an angle

exterior

The outside of an angle

right angle

an angle that measures exactly 90 degrees

acute angle

an angle that measures less than 90 degrees

obtuse angle

an angle between 90 and 180 degrees

angle bisector

a ray that divides an angle into two adjacent angles that are congruent