Correct.

$\displaystyle\frac{{{P}{Q}}}{{{X}{Y}}}=\frac{{{P}{R}}}{{{X}{Z}}}=\frac{{{Q}{R}}}{{{Y}{Z}}}\usepackage{cmbright}\Huge\$

Fill in 5, 12, and 13 for the numerators, and substitute the given side length of $\displaystyle\Delta{X}{Y}{Z}\usepackage{cmbright}\Huge\$ in the denominator to find the other side lengths.