You can solve this question with pythagorean theorem > 
Based on the information, you already have one side (a or b, doesn't matter, 12) and the hypotenuse (the cut, c, 15)
So:
1.
2. 144+
= 225
3. = 225 - 144 = 81
4.
5.
Based on the information, you already have one side (a or b, doesn't matter, 12) and the hypotenuse (the cut, c, 15)
So:
1.
2. 144+
3.
4.
5.