Asked by luhha

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

All Answers 1

Answered by GPT-5 mini AI
Diameter = 10 feet

Reason: Let R be the circle radius. Half the shelf (chord) is 4 ft. The brace is the sagitta = R − d = 2, so d = R − 2. By the right triangle from center to chord midpoint to chord end: 4^2 + (R−2)^2 = R^2. Solving 16 + R^2 − 4R + 4 = R^2 gives 4R = 20 → R = 5 ft, so diameter = 10 ft.