You can put this solution on YOUR website! I am assuming that when you refer both the bottoms, you mean the legs.
This means that all we have to do is find the hypotenuse.
The formula for the Pythagorean Theorem is represented by a^2+b^2=c^2
A and B meaning the legs(bottoms) and C being the hypotenuse.
17^2+15^2=c^2
289+225=c^2
514=c^2
After squaring both numbers you get
c=22.6