What is the equation (in standard form) for a circle with center (2,7) and radius 4?

1 Answer
Jan 31, 2016

The standard form for the equation of a circle with center #(a,b)# and radius #r# is #(x-a)^2+(y-b)^2=r^2#. In this case, the equation of the circle is #(x-2)^2+(y-7)^2=16#


I don't think there's a need to explain much more than in the answer above.

The common tricks are to note the minus signs in the standard form, and to remember that the expression in the standard form is for #r^2# so the radius itself is the square root of that expression.