Q.

Let the centre of a circle, passing through the points (0, 0), (1, 0) and touching the circle x2+y2=9, be (h, k). Then for all possible values of the coordinates of the centre (h, k), 4(h2+k2) is equal to _________.          [2024]


Ans.

(9)

Circle will touch internally

∴ C1C2=|r1–r2|

⇒ h2+k2=3–h2+k2 ⇒ 2h2+k2=3

⇒ h2+k2=94    ∴ 4(h2+k2)=9.