A right angle is an angle that is exactly 90 degrees. When an angle is 90 degrees, one leg of the angle is perfectly horizontal, and the other is perfectly vertical. It is the best angle for creating stable structures. You can find more information here: http://www.mathsisfun.com/rightangle.html
2 Additional Answers
Ask.com Answer for:
what is a right angle
the angle formed by two radii of a circle that are drawn to the extremities of an arc equal to one quarter of the circle; the angle formed by two perpendicular lines that intersect; an angle of 90°.