Correct. Given $\displaystyle{a}={b}={x}\usepackage{cmbright}\Huge\$ and $\displaystyle{c}={5}\sqrt{{2}}\usepackage{cmbright}\Huge\$ , the Pythagorean Theorem says that $\displaystyle{{x}}^{{2}}+{{x}}^{{2}}={{\left({5}\sqrt{{2}}\right)}}^{{2}}={25}{\left({2}\right)}={50}\usepackage{cmbright}\Huge\$ , so $\displaystyle{2}{{x}}^{{2}}={50}\usepackage{cmbright}\Huge\$ , and therefore $\displaystyle{x}={5}\usepackage{cmbright}\Huge\$ .