The Pythagorean theorem consists of a formula a^2+b^2=c^2 which is used to figure out the value of (mostly) the hypotenuse in a right triangle.
[tex]\begin{gathered} c=\sqrt[]{a^2+b^2} \\ c=\sqrt[]{54^2+72^2} \\ c=\sqrt[]{8100} \\ c=90 \end{gathered}[/tex]The answer would be c = 90