Answer
distance $ = \sqrt{ (x_{2} - x_{1})^{2} + (y_{2} - y_{1})^{2} }$
Work Step by Step
The equation and derivation for the distance between points formula is found on the bottom half of page $18$. The example uses the points $(x_{1}$ , $y_{1})$ and $(x_{2}$ , $y_{2})$ to produce the formula $ = \sqrt{ (x_{2} - x_{1})^{2} + (y_{2} - y_{1})^{2} }$, which is the answer to our question.