The Pythagorean theorem tells you the square on the hypotenuse is equal to the sum of the squares on the other two sides. (This is the version you use for problem 2.)
This also means the square on one side is the difference between the square on the hypotenuse and the square on the other side. (Use this version for problems 1 and 3.)
1. ? = 200 in² -75 in² = 125 in²
2. ? = 576 km² + 100 km² = 676 km²
3. ? = 36 square units - 16 square units = 20 square units
