EXPLANATION
If the area of a circle with radius r is given by nr^2 and the area of a circle is 16 square units.
So, the radius of the circle is as follows:

Isolating r:
![r=\sqrt[]{(16)/(n)}=\frac{4}{\sqrt[]{n}}=\frac{4}{\sqrt[]{1}}=4](https://img.qammunity.org/2023/formulas/mathematics/college/g2qunp1ao3glvek0q8b8pl6qb8tlgm6v3q.png)
So, the radius is 4 units because in this case, n is equal to 1, so sqrt(1) is zero.