Recalling the formula for the area of a circle:

Divide both sides of the equation by the constant pi :

Take the square root of both sides of the equation and take the positive value of the square root, since r is a length and it is positive:
![\sqrt[]{(A)/(\pi)}=\sqrt[]{r^2}=r](https://img.qammunity.org/2023/formulas/mathematics/college/2tlurjg1n9yscazutqxxe3u33gb1g5nzm7.png)
Therefore:
![r=\sqrt[]{(A)/(\pi)}](https://img.qammunity.org/2023/formulas/mathematics/college/8m10f0ajyg8lzllx33hft09frh505dbyuq.png)
Since A=25, then:
![r=\sqrt[]{(25)/(\pi)}=\frac{\sqrt[]{25}}{\sqrt[]{\pi}}=\frac{5}{\sqrt[]{\pi}}](https://img.qammunity.org/2023/formulas/mathematics/college/cmy1r5aw2b25bq5jcza4yyxf9ba03nl00i.png)
Use a calculator to find out the decimal representation of the number 5/sqrt(pi):
![r=\frac{5}{\sqrt[]{\pi}}\approx2.821](https://img.qammunity.org/2023/formulas/mathematics/college/v6y6oyhfbx4detdp9p3or9jbeah6x15qkf.png)
Therefore, the radius of a circle with area 25 is approximately 2.821.