#### Answer

$3.87$ inches

#### Work Step by Step

We are given that the area is $15$ inches. To find the side length we are calling it $x$ in the equation. The equation for area is $Area=x^{2}$, where $x$ is the side length.
We can write the equation as so since we are given the area of the figure. $Area=x^{2}=15$.
Because $x^{2}=15$, we are able to find the value of $x$ by finding the square root of $15$.
$\sqrt 15=3.87$
We now know the value of $x$, the side length, because $x\approx\sqrt {15}\approx3.87$.
$x=3.87$ or $x=\sqrt {15}$