Answer:
a)

b) 15
Explanation:
a) We know that AB = 8 and BC = x. We can use the Pythagorean Theorem, which states that for a right triangle with sides a, b, and c:
, where a and b are the shortest sides and c is the longest.
Here, AB = a = 8 and BC = b = x. So, AC = c. Then:



b) We know that AC - AB = 9. Since AB = 8, then AC = 9 + 8 = 17. We also have the expression from above, so set them equal:



x = 15
Hope this helps!