The equation of the circle is S≡x2+y2−6x+12y+15=0 Let the equation of concentric circle of given circles, is S2=x2+y2−6x+12y+15=0 On comparing the circle S1 with, x2+y2+2gx+2fy+c=0 ⇒‌‌g=−3,f=6,c=15 Then, radius of circle is ‌=√g2+f2−c ‌=√9+36−15 ‌=√45−15=√30‌ units ‌ and centre is (−g,−f)=(3,−6) Now, the area of the circle S is =π (radius) ‌2 ‌=π(√30)2 ‌=30π Let the radius of the concentric circle is r2. r2‌=√g2+f2−c ‌=√9+36−c ‌=√45−c Then, according to question, the area of concentric circle ‌=2×‌ area of ‌S ‌2×30π=60π ⇒πr22‌=60π ⇒‌(√45−c)2‌=60 ⇒‌45−c‌=60 ⇒‌c‌=−15 Hence, the equation of concentric circle is x2+y2+2(−3)x+2(6)y+(−15)=0 x2+y2−6x+12y−15=0