Answer: 5
Step-by-step explanation:
As all radii of a circle are congruent, [tex]\overline{OX} \cong \overline{OY}[/tex], it follows that [tex]\angle OXY \cong \angle OYX[/tex].
Because arc XY measures 60 degrees, we also know that [tex]m\angle XOY=60^{\circ}[/tex], and thus triangle OXY is equilateral.
Hence, XY=5 because all sides of an equilateral triangle are congruent.