what is a 90 degree angle

A 90-degree angle is a right angle, which is an angle of exactly 90 degrees or π/2 radians corresponding to a quarter turn. It is exactly half of a straight angle and always corresponds to a quarter turn. When two lines intersect each other and the angle between them is 90 degrees, then the lines are said to be perpendicular. A right angle can be drawn using a protractor and compass. In geometry, right angles are fundamental and are defined as two straight lines intersecting to form two equal and adjacent angles.