The area of a square given its diagonal (d) is computed as follows:
[tex]A=\frac{1}{2}d^2[/tex]
In this case, the diagonal is 10 units long, then the area is:
[tex]\begin{gathered} A=\frac{1}{2}\cdot10^2 \\ A=\frac{1}{2}\cdot100 \\ A=50\text{ square units} \end{gathered}[/tex]
