


Pythagoras TheoremDistance Between Two PointsWe use the Pythagoras Theorem to derive a formula for finding the distance between two points in 2 and 3 dimensional space. Let P = (x _{1}, y _{1}) and Q = (x _{2}, y _{2}) be two points on the Cartesian plane (see picture below).
Then from the Pythagoras Theorem we find that the distance between P and Q is
In a similar way, it can be proved that if P = (x _{1}, y _{1}, z_{1}) and Q = (x _{2}, y _{2}, z_{2}) are two points in the 3dimensional space, the distance between P and Q is
Exercise 1. << Pythagorean Triples  Pythagoras Theorem Index
