Answer
48
Work Step by Step
The length of one part of one of the missing sides is 6, for it forms a miniature rectangle where it is opposite the side of length 6. In addition, the other additional part missing has a length of: $l = \sqrt{17^2 - 8^2} = 15$. Now, we consider the other missing length of the other missing side: $l = \sqrt{8^2 + 6^2} =10$
$P = 17 + 10 + 6 + 15 = 48$
