Equation of circle whose radius is 5 and which touches the circle x2+y2−2x−4y−20=0  at (5, 5) is

C1=(1,2)    r1=5 C2=(h,k)   r2=5As the two circles radii are same the point where the two circles touch each other is the midpoint of the centres(5,5)=(h+12,k+22)⇒(h,k)=(9,8)∴(x−9)2+(y−8)2=25