## Elementary Algebra

$c = 5\sqrt 2$
Using Pythagorean Theorem, $a^2 + b^2 = c^2$, and plugging in the values for a and b, gives $1^2 + 7^2 = c^2$, which can be simplified to $1+49=c^2$ To solve $c^2 = 50$, we take the square root of both sides, giving $c = \sqrt 50 = \sqrt (25\times2)=5\sqrt2$