Question 218932
the  standard  form  for a  circle  is,,,(x-h)^2 +(y-k)^2 = r^2
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with  (h,k) as  center  of  circle,,and  r  as  radius
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with  center  at (2, -4),,,,,h= 2,,,k= -4,,,and  radius  is  the  x distance from  center  to  x=-2,,,|(-2-2)| = |(-4)| = 4
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substituting,  (x-2)^2 + (y-(-4) )^2 =4^2 =16
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(x-2)^2 +(y+4)^2 = 16,,,,answer
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a  rough  sketch  shows  how  this  is  possible  on  the  x-y  coordinate  system.
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