Section 2.1: Geometry Basics

Section 2.1 – Geometry Basics

A point is simply a location, which has no dimensions! That might seem strange, but the geometric idea of a point is that it has no length, no width, and no height.

Any two distinct points, we now can form a line connecting the two points. A line is a one-dimensional figure (it has length, but no width and no height) that is made up of an infinite number of individual points placed side by side. In geometry all lines are assumed to be straight; if they bend they are called a curve. A line continues infinitely (forever) in two directions, usually indicated by placing arrows at the two ends.

A line segment does not continue infinitely in two directions, but has two endpoints, usually indicated by placing points at the two ends.

A plane is a flat surface that continues forever (or, in mathematical terms, infinitely) in every direction. It has two dimensions: length and width. You can visualize a plane by placing a piece of paper on a table. Now imagine that the piece of paper stays perfectly flat and extends as far as you can see in four directions, left-to-right and front-to-back.