Final answer:
The number of degrees between the lower and upper arm of an angle is called the Angle measure, which specifies the amount of rotation from one arm to the other. A full circle is 360°, and angles can also be expressed in radians.
Step-by-step explanation:
The number of degrees between the lower and upper arm of an angle is called the Angle measure. An angle, which can be visualized as the space between two intersecting lines or rays, is quantified in degrees (°). A full circle contains 360°, which means if you divided the circle into 360 equal parts, the angle between one side of a slice and the other is 1°. Similarly, half of a circle, or a straight angle, measures 180°.
Angles can be further divided into minutes and seconds, where one degree contains 60 minutes (') and one minute contains 60 seconds ("). The notation is such that 35° 43' 9" would mean 35 degrees, 43 minutes, and 9 seconds. Astronomers, for example, use degrees, minutes, and seconds to measure the separation between celestial objects. Additionally, in mathematics, radians are another unit used to measure angles; there are 2π radians in a full revolution, or 360°.