Find the area of the shaded region.

The figure shows a circle with center O and radius $r = OA = OB = 5$ cm.
TA and TB are tangents to the circle from an external point T.
The distance from the center to the external point is $OT = 13$ cm.
The angle $\angle AOT = 60^\circ$.
The shaded area is the area of the quadrilateral OATB minus the area of the sector AOB.

In a circle, a tangent is perpendicular to the radius at the point of tangency. Therefore, $\angle OAT = 90^\circ$.
Consider the right-angled triangle $\triangle O