If one of the diameters of the circle x2+y2-10x+4y+13=0 is a chord of another circle C, whose center is the point of intersection of the lines 2x+3y=12 and 3x-2y=5, then the radius of the circle C is :
- 4
- 3 2
- 6
- 20
Answer
(3) 6
Solution
Given circle: centre M(5, -2), radius = 25+4-13=4
2x+3y=12, 3x-2y=5 ⇒ centre of C is (3, 2)
[figure]
M is the mid-point of chord PQ of circle C ⇒ CM PQ
CM2=(5-3)2+(-2-2)2=20
radius =CP= CM2+MP2= 20+16=6
Answer: (3)