#### Answer

b=15

#### Work Step by Step

The Pythagorean Theorem states that for a right triangle, $a^{2} +b^{2} = c^{2}$. Thus, we plug in the values given for a, b, or c, and then we use these values to find the missing value:
$8^{2} + b^{2} = (17)^{2} \\\\ 64 + b^{2} =289 \\\\ b^{2} =225 \\\\ b=15$