VITEEE 2013 Paper

Let (h, k) be any point in the set, then equation of circle is
(x−h)2+(y−k)2 = 9

(h, k) lies on x2+y2 = 25, then h2+k2 = 25
⇒ 2 ≤ Distance between the two circles ≤ 8
⇒ 2 ≤ √h2+k2 ≤ 8
⇒ 4 ≤ h2+k2 ≤ 64
∴ Locus of (h, k) is 4 ≤ (x2+y2) ≤ 64