LINES AND ANGLES

A. ANGLES

1. DEFINITION OF ANGLE

Consider the following figure.

Rays AB and BC are called  the legs of the angle (kaki sudut). The common end point of legs of the angle is called the vertex (titik sudut). An area formed by two sides of legs of the angle is the area of angle  (Daerah sudut). Area of angle BAC next is called the measure of BAC and it  is denoted by  BAC.

You can denoted the angle in two ways, using one letter or using three letters. If you denote the angle using three letters, then the name of the vertex will be placed in the middle of the name of the angle.

Example:

Denote the following angle using one letter and three letters.

Solution:

• If the angle is denoted by a letter, then the name is

 Q. You can also denote an angle using Greek letter, for example .

• If the angle is denoted by three letters, then the name is

PQR.