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JEE Main 201323 AprilOnline
Exam
JEE Main
Year
2013
Date
23 April
Mode
Online
Subject
Mathematics
Chapter
Circle

JEE Main 2013 · 23 April · Online · Mathematics · Circle

If the circle x^2+y^2-6 x-8 y+(25-a^2)=0 touches the axis of x ,...

If the circle x2+y2−6x−8y+(25−a2)=0x^2+y^2-6 x-8 y+\left(25-a^2\right)=0 touches the axis of xx, then a equals.If the circle x^2+y^2-6 x-8 y+(25-a^2)=0 touches the axis of x , then a equals.If the circle x^2+y^2-6 x-8 y+(25-a^2)=0 touches the axis of x , then a equals.

Options

  1. A0
  2. B±4\pm 4
  3. C±2\pm 2
  4. D±3\pm 3

Correct answer

B. ±4\pm 4

Step-by-step solution

If the circle x^2+y^2-6 x-8 y+(25-a^2)=0 touches the axis of x , then a equals.
x2+y2−6x−8y+(25−a2)=0 Radius =4=9+16+(25−a2)⇒a=±4\begin{aligned}& x²+y²-6 x-8 y+\left(25-a²\right)=0 \\ & \text{ Radius }=4=\sqrt{9+16+\left(25-a^2\right)}\\ & \Rightarrow \mathrm{a}=\pm4 \end{aligned}
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