1. **Problem:** Find the area of a circle with radius 15 ft. 2. **Formula:** The area of a circle is given by $$A = \pi r^2$$ where $r$ is the radius. 3. **Calculation:** Here, $r = 15$ ft. $$A = \pi (15)^2 = \pi \times 225 = 225\pi$$ ft² 4. **Answer:** The area is $225\pi$ ft². --- 1. **Problem:** Find the area of a circle with diameter 22 in. 2. **Formula:** Radius $r = \frac{d}{2}$, so $r = \frac{22}{2} = 11$ in. 3. **Calculation:** $$A = \pi r^2 = \pi (11)^2 = 121\pi$$ in² 4. **Answer:** The area is $121\pi$ in². --- 1. **Problem:** Find the area of a circle with radius 9 yd. 2. **Formula:** $$A = \pi r^2$$ 3. **Calculation:** $$A = \pi (9)^2 = 81\pi$$ yd² 4. **Answer:** The area is $81\pi$ yd². --- 1. **Problem:** Find the area of a circle with diameter 12 yd. 2. **Formula:** Radius $r = \frac{12}{2} = 6$ yd. 3. **Calculation:** $$A = \pi (6)^2 = 36\pi$$ yd² 4. **Answer:** The area is $36\pi$ yd². --- 1. **Problem:** Find the area of a circle with radius 3 in. 2. **Formula:** $$A = \pi r^2$$ 3. **Calculation:** $$A = \pi (3)^2 = 9\pi$$ in² 4. **Answer:** The area is $9\pi$ in². --- 1. **Problem:** Find the area of a circle with diameter 34 ft. 2. **Formula:** Radius $r = \frac{34}{2} = 17$ ft. 3. **Calculation:** $$A = \pi (17)^2 = 289\pi$$ ft² 4. **Answer:** The area is $289\pi$ ft². --- 1. **Problem:** If the radius is 10 ft, what is the area? 2. **Formula:** $$A = \pi r^2$$ 3. **Calculation:** $$A = \pi (10)^2 = 100\pi$$ ft² 4. **Answer:** The correct choice is a) $100\pi$ ft². --- 1. **Problem:** Find the area of a circle with diameter 16 in. 2. **Formula:** Radius $r = \frac{16}{2} = 8$ in. 3. **Calculation:** $$A = \pi (8)^2 = 64\pi$$ in² 4. **Answer:** The correct choice is b) $64\pi$ in². --- 1. **Problem:** A cow is tethered with a rope 20 ft long. Find the maximum grazing area. 2. **Formula:** The rope length is the radius $r = 20$ ft. 3. **Calculation:** $$A = \pi (20)^2 = 400\pi$$ ft² 4. **Answer:** The maximum grazing area is $400\pi$ ft².