JEE Main 2020 — Circle Question with Solution
From: JEE Main 2020 (Online) 8th January Evening Slot
Question
If a line, y = mx + c is a tangent to the circle,
(x – 3)2 + y2 = 1 and it is perpendicular to a line L1, where L1 is the tangent to the circle, x2 + y2 = 1 at the point , then :
Choose an option
Show full solutionCorrect option: A
Correct answer
Ac2 + 6c + 7 = 0
Step-by-step explanation
For circle x2 + y2
= 1 tangnet at point P is
T = 0
x + y - = 0
Perpendicular to the line is
x - y + c = 0
This is tangent to the circle (x – 3)2 + y2 = 1
Also we know, perpendicular distance from center = radius
= 1
|3 + c| =
9 + c2 + 6c = 2
c2 + 6c + 7 = 0
T = 0
x + y - = 0
Perpendicular to the line is
x - y + c = 0
This is tangent to the circle (x – 3)2 + y2 = 1
Also we know, perpendicular distance from center = radius
= 1
|3 + c| =
9 + c2 + 6c = 2
c2 + 6c + 7 = 0
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