The radical axis of the circles, belonging to the coaxal system of circles whose limiting points are (1, 3) and (2, 6), is

Options

A. `x-3y-15=0`
B. `x+3y-15=0`
C. `x-3y+15=0`
D. `2x+3y-15=0`

Answer

B

Explanation

We know that the limiting points are circles of the coaxial system with zero radius. The equations of the point circles having (1, 3) and (2, 6) as limiting points are
`S_(1)=(x-1)^(2)+(y-3)^(2)=0` ...(i)
and, `S_(2)=(x-2)^(2)+(y-6)^(2)=0` ...(ii)
The equation of their radical axis is
`S_(1)-S_(2)=0 rArr x+3y-15=0`.