Using the intersecting chord theorem: A circle is shown. The shelf is represented by a chord and the brace goes from the chord to to a point on the circle. The brace line is extended up to form a diameter.
Custom drapes are being fitted for a large circular window. It is difficult to get these measurements, but the window has an 8 ft horizontal shelf with a 2 ft brace that sits in the frame. If the brace is extended upward, it would go through the center of the shelf and the circle. What is the diameter of the window?

Diameter =
feet