Answer:
16 units
Explanation:
You want the side length of a square pyramid with height 15 units and slant height 17 units.
Pythagorean theorem
The Pythagorean theorem can be used to find the distance from the midpoint of one side to the center of the square base.
(b/2)² +15² = 17²
(b/2)² = 289 -225 = 64
b/2 = √64 = 8
Then the length of one side of the base is ...
b = 2·8 = 16 . . . . units