Perpendicular and Parallel Lines

There are three basic types of straight lines in geometry:

1. What is a Line Segment?

A line segment has two distinct endpoints. It does not go on forever — it starts at one point and ends at another.
Example: $\overline{AB}$

2. What is a Ray?

A ray has one endpoint and extends infinitely in one direction. It starts at a point and keeps going in one direction forever.
Example: $\overrightarrow{AB}$

3. What is a Line?

A line has no endpoints and extends infinitely in both directions. You can think of it as a never-ending path in both directions.
Example: $\overleftrightarrow{AB}$

Understanding perpendicular and parallel lines is useful because they show how lines connect or stay apart in geometry, constructions, and everyday objects.

🌟 What are Perpendicular Lines?

Two lines are perpendicular if they intersect at a right angle (90 degrees).
They form a perfect corner where they meet.
Example: $g\perp h$

🌟 What are Parallel Lines?

Two lines are parallel if they are always the same distance apart and never intersect, no matter how far they are extended.
They run side by side, like railway tracks.
Example: $l\parallel m$

In geometry, distances are measured using perpendicular or parallel lines, depending on the situation.

How to Measure Distance Between Two Points?

To measure the distance between two points, draw a straight line segment connecting them and measure its length with a ruler.

How to Measure Distance from a Point to a Line?

To measure the distance from a point to a line, draw a line segment from the point that meets the line at a right angle. The length of that segment is also the shortest distance.

How to Measure Distance Between Parallel Lines?

To measure the distance between two parallel lines, draw a line segment that is perpendicular to both lines. Measure the length of that segment.