They can not, there are only 2 sides and they probably flipped it different ways. They got 'lucky'.
Ratio: 2:7
2+7 = 9
747 / 9 = 83
83*2 = 166
83 * 7 = 581
166 to 581
A plane has two dimensions and extends infinitely in both dimensions.
To find the value of C: Use the Pythagorean Theorem
4^2 + 3^2 = c^2
16 + 9 = c^2
25 = c^2
sqrt of 25 = c
c = 5