# What does a line mean in geometry?

## What does a line mean in geometry?

A line is a straight one-dimensional figure having no thickness and extending infinitely in both directions. Euclid defined a line as a “breadthless length,” and a straight line as a line that “lies evenly with the points on itself” (Kline 1956, Dunham 1990). Consider first lines in a two-dimensional plane.

### Is parallel up and down?

Parallel lines as a purely geometric concept must be completely flat and exist on a single plane. In real life, while railroad tracks, the edges of sidewalks, and the markings on streets are all parallel, the tracks, sidewalks, and streets go up and down hills and around curves.

What is a line up and down called?

The terms vertical and horizontal often describe directions: a vertical line goes up and down, and a horizontal line goes across. You can remember which direction is vertical by the letter, “v,” which points down.

What is a line going up called?

Vertical lines, segments, or rays: Lines or parts of a line that go straight up and down are vertical.

## How do you represent a line in geometry?

A line in geometry is represented by a line with arrows at each end. A line segment and a line are different because a line goes on forever while a line segment has a distinct beginning and end.

### Does horizontal go up and down?

horizontal Add to list Share. The opposite of vertical, something horizontal is arranged sideways, like a person lying down. When you sleep (unless you’re a horse), your body is horizontal: horizontal things are parallel to the ground or running in the same direction as the horizon.

Does a vertical line go up and down?

Vertical lines go up and down and have a slope that is undefined. Graphs of horizontal lines are parallel to the x-axis. Graphs of vertical lines are parallel to the y-axis.

What does a straight up and down line mean in math?

A vertical line is one the goes straight up and down, parallel to the y-axis of the coordinate plane. All points on the line will have the same x-coordinate. In the figure above, drag either point and note that the line is vertical when they both have the same x-coordinate. A vertical line has no slope.

## What is the number of endpoints of a line?

two
A line has two end-points.

### How do you write a line in geometry?

When we draw lines in geometry, we use an arrow at each end to show that it extends infinitely.

1. A line can be named either using two points on the line (for example, ↔AB ) or simply by a letter, usually lowercase (for example, line m ).
2. A segment is named by its two endpoints, for example, ¯AB .