The distance between two points is given by the expression,
[tex]d = \sqrt{ {(y2 - y1)}^{2} + {(x2 - x1)}^{2} } [/tex]
Plugging in our values,
[tex]d \: = \sqrt{ {(1 - 9)}^{2} + {( - 4 - - 1)}^{2} } \\ d \: = \sqrt{ {( - 8)}^{2} + {( - 3)}^{2} } \\ d \: = \sqrt{64 + 9} \\ d = \sqrt{73} [/tex]
So, the distance between the points in it's exact radical form is
[tex] \sqrt{73} \: units[/tex]
