JEE Main 2021 — Circle Question with Solution
From: JEE Main 2021 (Online) 26th August Evening Shift
Question
A circle C touches the line x = 2y at the point (2, 1) and intersects the circle
C1 : x2 + y2 + 2y 5 = 0 at two points P and Q such that PQ is a diameter of C1. Then the diameter of C is :
C1 : x2 + y2 + 2y 5 = 0 at two points P and Q such that PQ is a diameter of C1. Then the diameter of C is :
Choose an option
Show full solutionCorrect option: A
Correct answer
A
Step-by-step explanation
(x 2)2 + (y 1)2 + (x 2y) = 0
C : x2 + y2 + x( 4) + y(2 2) + 5 = 0
C1 : x2 + y2 + 2y 5 = 0
S1 S2 = 0 (Equation of PQ)
( 4)x (2 + 4)y + 10 = 0 Passes through (0, 1)
= 7
C : x2 + y2 11x + 12y + 5 = 0
=
Diameter =
C : x2 + y2 + x( 4) + y(2 2) + 5 = 0
C1 : x2 + y2 + 2y 5 = 0
S1 S2 = 0 (Equation of PQ)
( 4)x (2 + 4)y + 10 = 0 Passes through (0, 1)
= 7
C : x2 + y2 11x + 12y + 5 = 0
=
Diameter =
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