Answer:
17
Step-by-step explanation:
Shape: Isosceles Right Triangle.
Isosceles Right Triangles always have two sides of equal length. In this case, the sides of equal length include 17 and 17. The third side (9) would refer to the base, so it would not count.
Also, if you turn the shape sideways, you can see that the unknown side would be 17.
Hope this helps!
