Question 102398
The distance between each pair of points can be computed using the Pythagorean formula. Imagine that the line between any two points is the diagonal of a right triangle.

Consider the (x, y) pairs: (2, 1.5) and (8, 6). One side of the triangle is defined by a line that runs parallel to the x-axis, starting at 2 and ending at 8. The other side of the right triangle is a line parallel to the y-axis that runs from 1.5 to 6. The length of the side parallel to the x-axis is simply the difference in the x values = 8 - 2 = 6.  The length of the side parallel to the y-axis (and therefore at right angles to the line parallel to the x-axis, by definition) is likewise the difference:  6 - 1.5 = 4.5.

So one side is 6 and the other 4.5. That means the diagonal line's length is the square root of ( 6^2 + 4.5^2 ).