The distance between two points
[tex]A=(x_1,y_1),\quad B=(x_2,y_2)[/tex]
is given by
[tex]d = \sqrt{(x_1-x_2)^2+(y_1-y_2)^2}[/tex]
as a direct application of Pythagorean theorem.
In your case, the points are
[tex]A=(6,-8),\quad B=(0,0)[/tex]
So, the distance is
[tex]d = \sqrt{(6-0)^2+(-8-0)^2}=\sqrt{36+64}=\sqrt{100}=10[/tex]
P(6,4) means
6 on x axis
on y axis
therefore by pythagoras theoram
36+64=[hypotenus]2
hypotenus=root 100
therfore distance between the origin and the point is root 100
