A 90-degree angle has an internal angle equivalent to 90 degrees and forms a perfect L shape. It is also known as a right angle.

Ninety-degree angles are found in both geometry and trigonometry. A small square in the angle's corner symbolizes it as 90 degrees. A circle contains 360 degrees, and a right angle is 90 of that 360 degrees. It is one-quarter of the full circle, which gives a 90-degree angle its L shape. A 90-degree angle can be rotated in any direction and still have an internal angle of 90 degrees. If a triangle has a 90-degree angle, it is known as a right triangle.