In geometry and trigonometry, an angle (in full, plane angle)'s the figure formed by two rays sharing a common endpoint, called the vertex of the angle . The magnitude of the angle's the "amount of rotation" that separates the two rays, and can be measured by considering the length of circular arc swept out when one ray's rotated about the vertex to coincide with the other (see "Measuring angles", below). Where there's no possibility of confusion, the term "angle"'s used interchangeably for bo… (More on Angle)