Study the following diagram, where point C lies in the exterior of circle O.
Segment WC is tangent to circle O at point W.
CO¯¯¯¯¯¯¯¯, CW¯¯¯¯¯¯¯¯¯, and OW¯¯¯¯¯¯¯¯¯ are drawn in to create △OWC.
Circle O as described, where O W equals r.

If WC=15 and CO=17, what is OW?
Enter the correct value.