# How do you use the Pythagorean Theorem to find the missing side of the right triangle with the given measures given c is the hypotenuse and we have b = 5, c = 8?

$a = \sqrt{39} \approx 6.245$
Pythagoras tells us that ${a}^{2} + {b}^{2} = {c}^{2}$
Hence ${a}^{2} = {c}^{2} - {b}^{2}$
So: $a = \sqrt{{c}^{2} - {b}^{2}} = \sqrt{{8}^{2} - {5}^{2}} = \sqrt{64 - 25} = \sqrt{39} \approx 6.245$