Let S=x2+y2=16 At point (0,0) S≡0+0−16=−16<0 At point (0,1) S=0+1−16=−15<0
Thus, both points lie inside the circle. It means required circle touch inside the given circle. So, the centre and radius of given circle are C(0,0) and r=4 since, the required circle is passing through centre (0,0) ∴ Diameter of required circle =4 and radius of required circle =‌