Let and are any two points on the line. We find the distance between P and Q.

For This draw PM and QN perpendicular to X–Axis.

From P draw PR perpendicular to QN.

Consider the right angle triangle

I. First we find the distance between P and R.

II. Secondly, we find the distance between R and Q.

III. Finally, we find the distance between P and Q.

By using Pythagorean Theorem

We have