Question 97513

 the general equation of a circle is 

  {{{(x-x1)^2 + (y-y1)^2 = r^2 }}} where (x1,y1) is the center of the circle and
 r its radius

given 
 equation of the circle
  {{{ (x-2)^2 + (y + 3)^2 = 16 }}}

rewriting this equation in the standard form 
  {{{ (x-2)^2 + (y - (-3))^2 = 4^2 }}}

clearly the centre is (2,-3) and the radius 4