A circle is described by the equation left parenthesis x space minus space 3 right parenthesis to the power of 2 space end exponent plus space left parenthesis y space plus space 2 right parenthesis squared space equals space 81. Find the radius of the circle. Then calculate the circumference of the circle. (Leave in terms of straight pi.) The radius of the circle is units. The circumference of the circle is straight pi units