How did you determine a line segment​

First, find the distance between the x-coordinates. To do this, subtract one number from the other and then take its absolute value.

Then repeat with the y-coordinates.

Finally, to compete the length (or distance), square BOTH values, add them, and take the square root.

By the way, what you are actually doing is using the Pythagorean Theorem on an imaginary right triangle with the line joining the two lines being the hypotenuse.

Hope this helps :))