How these points appear in xy plane, is shown in the
attached picture. If we calculate the distances using the formula for the
distance of between two points, [tex] \sqrt{(x_{1} - x_{2} )^{2} +(y_{1} - y_{2} )^{2} } [/tex], where [tex] x_{1} [/tex] , [tex] y_{1} [/tex] and [tex] x_{2} [/tex] , [tex] y_{2} [/tex] are the coordinates of the points. We find that the distance from the point (8;3) to (2;5) and to (2;1) is equal. And that's why it is an isosceles triangle.
