Question
Question: The line 2x – y + 1 = 0 is tangent to the circle at the point (2, 5) and the centre of the circle l...
The line 2x – y + 1 = 0 is tangent to the circle at the point
(2, 5) and the centre of the circle lies on x –2y = 4. The radius of the circle is:
A
35
B
53
C
25
D
52
Answer
35
Explanation
Solution
Let centre is (4 + 2B, B);
r = = (2B +2)2 + (5 –B)2 ; B = 1
Centre (8, 2), Radius = 35