How do you identify the center and the radius of the circle with equation #(x - 3)^2 + (y + 1)^2 = 81#?
centre (3 ,-1) , r=9
The standard form of the equation of a circle is.
where (a ,b) are the coordinates of the centre and r , the radius.
For the given equation: a = 3 , b = -1 and r = 9
hence centre = (3 ,-1) and radius = 9