Answer: In euclidian geometry, an angle is the figure formed by two rays , called the sides of the angle, sharing a common endpoint, called the vertex of the angle . 1.) Angles formed by two rays lie in the plane that contains the ray. Angles are also formed by the intersection of two planes . These are called dihedral angles 2.) Intersecting curves define also an angle, which is the angle of the tangents at the intersection point. For example , the spherical angle formed by two great circles on a sphere equals the dihedral angle between the planes containing the great circle.