The parts are arm vertex and ore
You can tell if a ray is bisecting an angle if the angle is cut directly in half into two congruent parts.
Acute Angle: An angle whose measure is less than 90 degrees and greater then zero degrees is called an acute angle. Right Angle: An angle whose measure is 90 degrees is called right angle. Obtuse Angle: An angle whose measure is greater than 90 degrees and less than 180 degrees is called obtuse angle. Straight Angle: An angle whose measure is 180 degrees called a straight angle. Reflex Angle: An angle whose measure is greater than 180 degrees and less than 360 degrees is called a reflex angle. Complete Angle: An angle whose measure is 360 degrees is called a complete angle. Zero Angle: If the measure of an angle is zero it is called a zero angle.
It is called an arm of the angle.
Bisecting an angle
Such a ray is called a "bisector" of the angle.
An angle bisector is a line. A bisector is something that cuts something into two equal parts. The line passes through the angle dividing it into two equal parts and is called an angle bisector.
Whats the angle? It is called bisecting an angle. The size of the angle does not need to be known if you are bisecting geometrically, though if doing it mathematically then a numerical value is required.