If a circle C passing through the point (4, 0) touches the circle 
externally at the point (1, −1), then the radius of C is :
(a)
(b)
4
(c)
(d)
5
If a circle C passing through the point (4, 0) touches the circle externally at the point (1, −1), then the radius of C is :
(a)
(b)
4
(c)
(d)
5
Question ID - 56779 | SaraNextGen Top Answer
If a circle C passing through the point (4, 0) touches the circle externally at the point (1, −1), then the radius of C is :
(a)
(b)
4
(c)
(d)
5
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If a circle C passing through the point (4, 0) touches the circle |
|||
|
(a) |
|
(b) |
4 |
|
(c) |
|
(d) |
5 |
1 Answer
127 votes
Answer Key / Explanation : (d) -
Equation of tangent at (1,
1)
x −y + 2(x+1) − 3(y 
1) – 12 = 0
3x 
4y − 7 = 0
Equation of circle is
It passes through (4, 0) :
(16 +16 − 12) + 
(12 − 7) = 0
⇒ 20 + 
(5) = 0
⇒ 
= 
4
Or 
+
Radius = 
127 votes
Answer Link
127