Complex sentence: In geometry, an angle (basically) is the region between two rays produced from a single point, called the "sides" of the angle, sharing a common endpoint, called the "vertex" of the angle.
Split into simpler sentences: In geometry, an angle (basically) is the region between two rays produced from a single point. The rays are called the "sides" of the angle, sharing a common endpoint, called the "vertex" of the angle.