Answer
5 $in^{2}$
Work Step by Step
The length of the diagonal of the square d = $\sqrt 10 $ in.
We know the area of the square whose diagonal has length d is A = $\frac{1}{2} d^{2}$
therefore A = $\frac{1}{2} \sqrt 10^{2}$
= $\frac{1}{2}$ * 10 = 5 $in^{2}$
