ABSTRACT
When two straight lines meet at a point an angle is formed as shown in Figure 10.1. There are two ways in which an angle can be denoted, i.e. either CAB or A.
The size of an angle depends on the amount of rotation between two straight lines, as illustrated in Figure 10.2. Angles are usually measured in degrees, but they can also be measured in radians. A degree, defined as 1/360 of a complete revolution, is easier to understand and use as compared to the radian. Figure 10.2 shows that the rotation of line AB makes 1/4 revolution or 90°, 1/2 revolution or 180°, 3/4 revolution or 270° and a complete revolution or 360°. For accurate measurement of an
Figure 10.1
LEARNING OUTCOMES:
10.1 Angles
60 minutes in a degree and 60 seconds in a minute. This method is known as the sexagesimal system:
60 minutes (60) 1 degree 60 seconds (60) 1 minute (1)
The radian is also used as a unit for measuring angles. The following conversion factors may be used to convert degrees into radians and vice versa.
