Correct. The ladder, wall, and ground form a right triangle; $\displaystyle{a}={5}\usepackage{cmbright}\Huge\$ , $\displaystyle{b}={10}\usepackage{cmbright}\Huge\$ and the length of the ladder is c. Using the Pythagorean Theorem, $\displaystyle{{c}}^{{2}}={{a}}^{{2}}+{{b}}^{{2}}={{5}}^{{2}}+{{10}}^{{2}}={25}+{100}={125}\usepackage{cmbright}\Huge\$ , so $\displaystyle{c}=\sqrt{{{125}}}\usepackage{cmbright}\Huge\$ , which is approximately 11.18 feet.