QR = 4 unit
Let us find RS, which is the length of the rectangle . Therefore
[tex]\begin{gathered} RS=\sqrt[]{(1-5)^2+(-4-6)^2} \\ RS=\sqrt[]{16+100} \\ RS=\sqrt[]{116} \end{gathered}[/tex][tex]\begin{gathered} \text{area}=lw \\ \text{area}=\sqrt[]{116}\times4 \\ \text{area}=4\sqrt[]{116\text{ }}unit^2 \end{gathered}[/tex]