[tex]\sqrt{a}=b\iff b^2=a\ for\ a\geq0\ and\ b\geq0\\\\\sqrt{\dfrac{1}{144}}=\dfrac{\sqrt1}{\sqrt{144}}=\dfrac{1}{12}\\\\\\\sqrt1=1\ because\ 1^2=1\\\\\sqrt{144}=12\ because\ 12^2=144[/tex]
