Angle \(\angle AOK\) is a central angle because its vertex is located at the center \(O\) and whose sides \(\overline{OA}\) and \(\overline{OK}\) are the radii of the circle which terminate at the points on the circle \(A\) and \(K\).

central angle AOK

The central angle \(\angle AOK\) intercepts the minor arc \( \overset{\Large\frown}{AK}\). Remember that the measure of a central angle is equal to the measure of its related arc. 

Because \(m\angle AOK = 85^\circ\) it implies that \( m\overset{\Large\frown}{AK}=85^\circ\)

minor arc AK