Variation Exercise 1  Distance Formula
Verify that the distance D id given by the formula is as stated
below by applying the Pythagorean Theorem to the triangle formed by
the points (x_{1}, y_{1}) and (x_{2}, y_{2})
as shown below.
STATEMENT 
JUSTIFICATION 
(x_{1}, y_{1})
and (x_{2}, y_{2}) are two given points. 
Given

