Let the set of all values of r, for which the circles (x+1)^2+(y+4)^2=r^2 and x^2+y^2-4 x-2 y-4=0 intersect at two distinct points be the interval…
JEE Main 2026 — Mathematics Coordinate Geometry
2026mcqmedium
Let the set of all values of r, for which the circles (x+1)2+(y+4)2=r2 and x2+y2−4x−2y−4=0 intersect at two distinct points be the interval (α,β). Then αβ is equal to
Official previous-year question
Held on 22 Jan 2026 · Verified 6 Jul 2026.
Options
A
21
B
24
C
20
D
25
Did you get this right?
Sign in to track your attempts and accuracy.
Solution
Circle 1: center C1=(−1,−4), radius r.
Circle 2: (x−2)2+(y−1)2=9, center C2=(2,1), radius 3.
Distance d=9+25=34.
For two intersection points: ∣r−3∣<34<r+3.
r+3>34⇒r>34−3 and ∣r−3∣<34⇒r<34+3.
r∈(34−3,34+3), so α=34−3, β=34+3.
αβ=(34)2−9=34−9=25.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.