Let's say the shorter side is x.
So, the longer side would be ( 7 + x )
Now we have to use the Pythagorean Theorem to find the value of x.
a² + b² = c²
( 7 + x )² + x² = 13
7² + x² + x² = 13²
49 + 2x² = 169
2x² = 169 - 49
2x² = 120
x² = 60
x = √60
So the longer side is ( 7 + √60 ) and the shorter side is √60