Now let's divide the second one through both sides of the equation:
+
And since ''l''<sub>1</sub> and ''l''<sub>2</sub> are whole numbers, what results when they are multiplied by themselves, namely ''l''<sub>1</sub><sup>2</sup> and ''l''<sub>2</sub><sup>2</sup>, certainly are as well.
So let's relabel ''l''<sub>1</sub><sup>2</sup> and ''l''<sub>2</sub><sup>2</sup>, ''o''<sub>1</sub> and ''o''<sub>2</sub>, to show they are natural numbers like the ''n''s
−
−
And separate out one leg-length factor from each leg-length-square fraction: