# Measure

In mathematics, measure can mean the amount of degrees in an angle, the length of a line segment, or a function that assigns a number to subsets of a given set.

## Line Segments

The measure of $\overline{AB}$ is indicated by $AB$, without the bar on top. If $\overline{AB}\cong\overline{CD}$, then $AB=CD$.

## Angles

The measure of $\angle ABC$ is indicated by $\mbox{m}\angle ABC$. If $\angle ABC\cong\angle DEF$, then $\mbox{m}\angle ABC=\mbox{m}\angle DEF$.

The measure of an angle can expressed in degrees or in radians.

## Circular arcs

The measure of an arc of a given circle is given by the measure of the central angle subtended by it.

## Sets

The measure of a set is known as the set's cardinality. If $S=\{-2,\,\pi,\,7\}$, then the cardinality of set $S$ is $3$.