i need help to a can get an A

Answer:
See below:
Step-by-step explanation:
We can use the Pythagorean Theorum to find out the missing side because we have a 90 degree right angle and 2 sides already given to us.
The Pythagorean Theorem states that a^2 + b^2 = c^2
a in this case would be the shortest side,
b in this case would be the 2nd longest side,
c is the hypotenuse.
[tex]a^{2} + b^{2}= c^{2} \\a^{2} + 15^{2} = 17^{2}[/tex]
If we solve this, we get 8!
Cheers!