In the given figure, $R$ is the center of the circle. The circle touches $X$ axis at $S(7,0)$ and intercepts the $y$ axis with $PQ=48$ units. From this information, find the equation of the circle.
Let $R(h,k)$ be the center of the circle. Then $h=7$. Let the equation of circle be $$x^2+y^2+2gx+2fy+c=0$$ The circle passes through $(7,0)$, so $$(7)^2+(0)^2+2g(7)+2f(0)+ c=0$$ $$49+0+14g +0+c=0$$ How do I proceed from here?