Points [tex](x,y)[/tex] on the circle satisfy [tex]x^2+y^2=100[/tex].
Points inside the circle satisfy [tex]x^2+y^2<100[/tex].
Points outside the circle satisfy [tex]x^2+y^2>100[/tex].
We have
[tex]2^2+8^2=4+64=68<100[/tex]
so the point (2, 8) lies inside the circle.