An angle is named using three letters, where the middle letter corresponds to the vertex of the angle. The angle at the right may be referred to as ∠

*ABC* or ∠

*CBA*. If it is perfectly clear which angle is being named, an angle may be referred to by its vertex letter alone, such as, in this case, ∠

*B*.

(See more about naming angles.)
It is understood, unless otherwise stated, that angles are positive, counterclockwise, and less than or equal to 180º.