Answer:
Diameter of pound = 10 yd
Explanation:
Given area of circular pond = 78.5 square yd
To find the diameter of the pond.
Solution:
The pond being circular in shape, the area of pond can be given as:
⇒
![\pi\ r^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/hp493qqffg80vwpug458zvs8wpnmu2ubnb.png)
where
represents radius of the pond.
Thus, we have:
⇒
![\pi\ r^2=78.5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/hlfp5yk8kdcerhfe8gd9eljpko68e68iau.png)
Using
![\pi=3.14](https://img.qammunity.org/2020/formulas/mathematics/middle-school/elnllul6m5wik5ibdc7x3b8auxqsmgjtbn.png)
⇒
![3.14r^2=78.5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/itxlhz2pndl4dwzlnn2xroa99s9zeejruj.png)
Solving for
![r](https://img.qammunity.org/2020/formulas/mathematics/high-school/mdw4pahxwshcsiue41gp04e4umejmucy5q.png)
Dividing both sides by 3.14
⇒
![(3.14r^2)/(3.14)=(78.5)/(3.14)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/s23wpxk0056t09x7qlzbtqxxz6v3sgz343.png)
⇒
![r^2=25](https://img.qammunity.org/2020/formulas/mathematics/middle-school/nm01qrkjp7c5st9z24jj33nx9476r24zve.png)
Taking square root both sides.
⇒
![√(r^2)=√(25)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vlm4xakn7w7i39cn5p5c5jwvxpk84e0rqb.png)
⇒
![r=\pm5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qntcw2gp8mj3nincnhkq3zdfez1k8r0402.png)
So, radius = 5 yd, as distances are always positive.
Diameter =
![2* radius=2* 5\ yd= 10\ yd](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mra7lj4bjolodruh6b8zih0n992u59x4un.png)
Thus, diameter of pound = 10 yd