Respuesta :

Answer:

Step-by-step explanation:

i think eq. of circle is

x²+y²-2x+4y-18=0

compare with x²+y²+2gx+2fy+c=0

center is (-g,-f) or (1,-2)

radius is √(g²+f²-c)=√((1)²+(-2)²-(-18))

=√(1+4+18)

=√23