geometry

a branch of mathematics that involves the measuring of shapes; actually means "to measure the earth"

point

represented by a dot

line segment

represented by a group of points having two endpoints

line

represented by a group of points having no endpoints that can extend indefinitely in two opposite directions

ray

represented by a group of points having one endpoint that can extend indefinitely in only one direction

angle

two rays that share a common endpoint

vertex

the common endpoint that two rays share

intersecting lines

lines that cross each other at some point

perpendicular lines

intersecting lines that form right angles

parallel lines

lines that never intersect

plane

represented by a smooth, flat surface that has nothickness and extends indefinitely in all directions