$\"\"$

The side lengths of a right triangle are $\"\"$ ; $\"c$ .

Apply Pythagorean theorem: $\"a$

$\"\"$ (Substitute 12 for a and 5 for b)

$\"\"$ (Evaluate powers: $\"\"$ ) $\"\"$

$\"\"$ (Add: $\"\"$ )

$\"\"$ (Take square root to each side)

$\"\"$ (Write $\"\"$ as $\"\"$ )

$\"\"$ (Cancel sqaure and root) $\"\"$

The unknown length of $\"\"$ .