Here's the question you clicked on:
iJiggl3
Given the right triangle ABC, with the right angle at C. If b=8 and c=17 use the Pythagorean Theorem to solve for a.
That's a bad question. If you need a diagram for this, you would need line segments to find the lengths. Also, you don't know if 8 and 17 are the hypotenuse. Which is why 15 might not be right.