Circle 1 Question 1

1. A circle touching the X-axis at (3,0) and making a intercept of length 8 on the Y-axis passes through the point

(2019 Main, 12 April II)

(a) (3,10)

(b) (3,5)

(c) (2,3)

(d) (1,5)

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Answer:

Correct Answer: 1. (a)

Solution:

  1. It is given that the circle touches the X-axis at (3,0) and making an intercept of 8 on the Y-axis.

Let the radius of the circle is ’ r ‘, then the coordinates of centre of circle are (3,r).

From the figure, we have

CM=3,CA= radius =r and AM=BM=AB2=4 Then, r2=CM2+AM2=9+16=25r=±5

Now, the equation of circle having centre (3,±5) and radius =5 is

(x3)2+(y±5)2=25

Now, from the options (3,10) satisfy the equation of circle

(x3)2+(y5)2=25



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