lines that intersect to form right angles polygon a closed figure with three or more sides Pythagorean theorem the formula a 2 + b 2 = c 2 , where a and b represent the lengths of the legs and c represents the length of the hypotenuse of a right triangle Pythagorean triple a set of three whole numbers that satisfies the Pythagorean theorem, a 2 + b 2 = c 2 , such as 3:4:5 and 5:12:13 quadrilateral a four-sided polygon radius a line segment inside a circle with one point on the radius and the other point at the center on the circle. The radius is half the diameter. This term can also be used to refer to the length of such a line segment. The plural of radius is radii . ray half of a line. A ray has one endpoint and continues infinitely in one direction. The geometric notation for a ray is with endpoint A and passing through point B is AB . rectangle a parallelogram with four right angles regular polygon a polygon with all equal sides rhombus a parallelogram with four equal sides right angle an angle that measures exactly 90° right triangle
