The radius of a circle is 9 inches. What is the area of a sector bounded by a 180 arc?

180/360 times 81 pi = 127.23 

The area of a sector bounded by a 180° arc of a circle with a radius of 9 inches is:

$$\frac{1}{2} \times \pi \times r^2 \times \frac{\theta}{360} = \frac{1}{2} \times \pi \times 9^2 \times \frac{180}{360} = \frac{1}{2} \times \pi \times 81 = \frac{81}{2} \pi \approx 127.23\text{ in}^2$$

Therefore, the area of the sector is approximately 127.23 square inches.  SkyWard Alpine Login