Angle whose vertex is inside a circle and whose sides are chords of the circle.

### Property

The degree measure of angle *CAF* below is equal to one-half the measure of the intercepted arc angle.

### Example

In the figure below, angle *CAF* is an interior angle of the circle with centre *O*.

Therefore: m\(∠\textrm{CAF} = \frac{\textrm{m} \widehat{\textrm{BE}}\space+\space\textrm{m}\widehat{\textrm{CF}}} {2}\)