Equation of a circle with radius 'r' and center (a, b) is (x−a)2+(y−b)2=r2
.
We have to convert the given equation in the above format.
Given,
x2 + y2 − 2x + 4y − 11 = 0x2−2x+y2+4y=11x2−2x+1+y2+4y+4=16(x−1)2+(y+2)2=42
Comparing these equations, we get r = 4.