Does Euclid’s fifth postulate imply the existence of parallel lines? Explain.
If a straight line l falls on two straight lines m and n such that sum of the interior angles on one side of l is two right angles, then by Euclid’s fifth postulate the lines m and n will not meet on this side of I. Next, we know that the sum of the interior angles on the other side of line l will also be two right angles.
Therefore, they will not meet on the other side also. So, the lines m and n never meet and are, therefore parallel.