1. The diagonal is the hypotenuse so,
√[12² + 12²] = 16.97
2. The same process is done
51.96
3. Again, use the Pythagorean theorem
35.78
4. The perimeter is 44, so the length of a side is 11, the diagonal is
15.57
5. The diagonal is 20, the formula is
d =s√2
where d is the diagonal and s is the side
s = 14.14