Custom drapes are being fitted for a large circular window. The window has an [tex]$8 \, \text{ft}$[/tex] horizontal shelf with a [tex]$2 \, \text{ft}$[/tex] 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 [tex]$=$[/tex] [tex]$\square$[/tex] feet



Answer :

To determine the diameter of the circular window, we can use some properties of circles and right triangles. Here's a step-by-step approach to solve the problem:

1. Identify the Known Measurements:
- The "horizontal shelf" is 8 feet long. This shelf acts as a chord of the circle.
- The "brace" is 2 feet long. This brace reaches from the midpoint of the chord to the center of the circle and is perpendicular to the chord.

2. Visualize the Geometry:
- Let's place the chord (shelf) horizontally with its midpoint directly below the center of the circle.
- The brace is a vertical line from the midpoint of the chord to the center.

3. Form a Right Triangle:
- The brace acts as one leg of the right triangle. Its length is 2 feet.
- Half of the chord's length is another leg of the right triangle. The length of half the chord is \( \frac{8}{2} = 4 \) feet.
- The radius of the circle is the hypotenuse of this right triangle.

4. Apply the Pythagorean Theorem:
- According to the Pythagorean theorem, in a right triangle with legs \( a \) and \( b \), and hypotenuse \( c \), the relationship is \( a^2 + b^2 = c^2 \).
- Here, \( a = 2 \) feet (brace), \( b = 4 \) feet (half-chord), and \( c \) (radius) is what we are trying to find.

5. Calculate the Radius:
- Substitute the known values into the Pythagorean Theorem equation:
[tex]\[ 2^2 + 4^2 = \text{radius}^2 \][/tex]
[tex]\[ 4 + 16 = \text{radius}^2 \][/tex]
[tex]\[ \text{radius}^2 = 20 \][/tex]
[tex]\[ \text{radius} = \sqrt{20} \approx 4.472 \][/tex]

6. Calculate the Diameter:
- The diameter of the circle is twice the radius.
- Therefore, the diameter \( \text{diameter} = 2 \times 4.472 \).

7. Final Answer:
- The diameter of the window is approximately \( \boxed{8.944} \) feet.

Thus, the diameter of the circular window is approximately 8.944 feet.