what is perpendicular

Perpendicular means “meeting at a perfect right angle,” that is, at 90 degrees.

What “perpendicular” means (in simple terms)

• Two lines are perpendicular if they cross each other and form a right angle (a neat square corner).

• A right angle is exactly 90 degrees, often shown with a little square in the corner.

• The word is used for lines, line segments, rays, and even for a line compared to a flat surface (a wall, floor, or plane).

A quick picture you can imagine: the corner of a book or the corner of most doors—that sharp corner is a right angle, so the two edges are perpendicular.

Everyday examples

• A person standing upright on level ground is perpendicular to the ground.

• The vertical edge of a wall and the flat floor usually meet at a right angle, so the wall is perpendicular to the floor.

• On a map or grid, a vertical street and a horizontal street that meet in a perfect “plus sign” shape are perpendicular streets.

In all of these, the key idea is the same: they meet at 90 degrees.

How it’s written in math

• The symbol for “is perpendicular to” is ⊥.

• If line AB is perpendicular to line CD, you write:
  AB‾⊥CD‾\overline{AB}\perp \overline{CD}AB⊥CD.

This is just a compact way of saying “AB and CD intersect at a right angle.”

Perpendicular vs. not perpendicular

• If lines never meet and always stay the same distance apart, they are parallel , not perpendicular.

• If lines do meet but the angle is not 90 degrees (it’s smaller or larger), they intersect but are not perpendicular.

So, “perpendicular” is a very specific kind of crossing: meet + right angle.

Information gathered from public forums or data available on the internet and portrayed here.