Angles are based on parts of a full turn, which is 360°. ... Slide 1 of 6, An image of four angles. The first shows two line segments making a right angle or ninety degrees.

Interior angles in a quadrilateral sum to a full turn (360˚). Image caption, Interior angles in a triangle add up to 180˚. ... Slide 1 of 8, An image of a square and an irregular quadrilateral.