Right angle

90° angle (π/2 radians): an angle that bisects the angle formed by two halves of a straight line
(Redirected from Perpendicular)

A right angle is an angle with a measurement of 90 degrees. When two lines cross each other so that all the angles have the same size, the result is four right angles. The top of the letter T is at right angles to the vertical line. Walls of buildings are usually at right angles to the floor. Two things that are at right angles are called "perpendicular" or "orthogonal". This is expressed using the symbol (such as in ).[1][2][3]

The little square indicates that this is a right angle

Planes (flat surfaces) can also meet at right angles. In a building, a wall and a floor are said to be perpendicular to each other, and they have a right angle. It also can be called a square angle.



  1. "List of Geometry and Trigonometry Symbols". Math Vault. 2020-04-17. Retrieved 2020-09-21.
  2. Weisstein, Eric W. "Perpendicular". mathworld.wolfram.com. Retrieved 2020-09-21.
  3. "Perpendicular - math word definition - Math Open Reference". www.mathopenref.com. Retrieved 2020-09-21.