bearing in mind that the distance from the center, to a point on the circle, is the radius unit.
[tex]\bf ~~~~~~~~~~~~\textit{distance between 2 points}
\\\\
\stackrel{center}{(\stackrel{x_1}{-2}~,~\stackrel{y_1}{3})}\qquad
(\stackrel{x_2}{-7}~,~\stackrel{y_2}{6})\qquad \qquad
% distance value
d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2}
\\\\\\
\stackrel{radius}{r}=\sqrt{[-7-(-2)]^2+[6-3]^2}
\implies r=\sqrt{(-7+2)^2+(6-3)^2}
\\\\\\
r=\sqrt{(-5)^2+3^2}\implies r=\sqrt{25+9}\implies r=\sqrt{34}[/tex]
