# Parallel vs. Perpendicular: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on January 13, 2024
Parallel lines never meet and maintain a constant distance, while perpendicular lines intersect at a 90-degree angle.

## Key Differences

Parallel lines run alongside each other at a consistent distance, never intersecting. Perpendicular lines, on the other hand, intersect at an exact 90-degree angle, forming corners.
In geometry, parallel lines are seen in shapes like rectangles and parallelograms. Perpendicular lines are evident in squares and rectangles, marking their corners.
Parallel lines maintain the same direction indefinitely. In contrast, perpendicular lines meet once and then diverge in two different directions.
On a grid or graph, parallel lines have the same slope, while perpendicular lines have slopes that are negative reciprocals of each other.
In everyday life, parallel lines can be seen in railway tracks, whereas perpendicular lines are seen in the crossing of streets.

## Comparison Chart

### Definition

Lines that never meet and are equidistant
Lines that intersect at a 90-degree angle

### Geometric Examples

Rectangles, parallelograms
Squares, rectangles

### Direction

Same direction indefinitely
Intersect and diverge in different directions

### Slopes (In Graphs)

Same slope
Negative reciprocals of each other

### Real-Life Examples

Railway tracks
Crossing of streets

## Parallel and Perpendicular Definitions

#### Parallel

In computing, parallel processing involves simultaneous data handling.
The supercomputer uses parallel processing for complex calculations.

#### Perpendicular

Perpendicular lines intersect at a right angle.
The corners of a square are perpendicular.

#### Parallel

Parallel describes things that are similar or analogous.
Their opinions on the matter were parallel to each other.

#### Perpendicular

In architecture, perpendicular style refers to a Gothic style.
The cathedral is known for its perpendicular Gothic architecture.

#### Parallel

In literature, parallel narratives run alongside each other.
The novel features parallel storylines that converge at the end.

#### Perpendicular

Perpendicular can describe an upright or vertical position.
The flagpole stands perpendicular to the ground.

#### Parallel

Parallel lines are equidistant lines that never intersect.
The two sides of a ladder form parallel lines.

#### Perpendicular

Perpendicular can mean something that directly opposes.
His views are perpendicular to the conventional wisdom.

#### Parallel

Parallel circuits have multiple paths for current to flow.
The electrical wiring in the house is set up in parallel circuits.

#### Perpendicular

Perpendicular forces act at right angles to a surface.
The pressure on the wing is perpendicular to its surface.

#### Parallel

Being an equal distance apart everywhere
Dancers in two parallel rows. See Usage Note at absolute.

#### Perpendicular

(Mathematics) Intersecting at or forming right angles.

#### Parallel

Of, relating to, or designating two or more straight coplanar lines that do not intersect.

#### Perpendicular

Being at right angles to the horizontal; vertical.

## FAQs

#### Do parallel lines have the same length?

Not necessarily; they can be of different lengths.

#### Can curves be parallel?

Yes, if they maintain a constant distance apart.

#### Are all intersecting lines perpendicular?

No, only if they intersect at a right angle.

#### Are parallel lines always straight?

In geometry, yes, they are straight lines.

#### Can three or more lines be perpendicular?

No, only two lines can be perpendicular to each other at a point.

#### How do you identify perpendicular lines?

They intersect at a 90-degree angle.

#### What is a key property of parallel lines?

They never intersect and maintain a constant distance.

#### Can perpendicular lines be extended?

Yes, but they will always remain perpendicular at the point of intersection.

#### How does the perpendicular style influence architecture?

It features vertical lines and elaborate window tracery.

#### What's an example of perpendicular forces in physics?

Gravity acting at a right angle to a plane surface.

#### Can parallel lines meet at infinity?

Theoretically in projective geometry, but not in Euclidean geometry.

#### How does slope relate to parallel lines?

Parallel lines have the same slope.

#### Is it possible to have parallel lines on a sphere?

No, due to the curvature, lines on a sphere eventually intersect.

#### Do perpendicular lines have to be the same length?

No, their lengths can vary.

#### Can two lines be both parallel and perpendicular?

No, it's not possible for lines to be both.

#### Can a line be parallel to itself?

In geometry, a line is always parallel to itself.

#### Are parallel lines always equidistant?

Yes, that's a defining property of parallel lines.

#### How are perpendicular lines used in construction?

For creating right angles in structures.

#### What instruments are used to draw perpendicular lines?

A set square or a right-angle ruler.

#### How are parallel lines used in mapping?

They're used as latitude lines on maps.