The number of common tangents to the circles x2+y2−4x−6y−12=0 and x2+y2+6x+18y+26=0, is

The coordinates of the centres and radii of the given circles are: C1:(2,3)      C2:(−3,−9)r1:5        r2:8we find that C1C2=13=r1+r2 So, the two circles touch each other externally. Hence, there are 3 common tangents.