Question

The radical axis of the coaxial system having the limiting points $(1,2)$ and $(4,3)$ is

• A. $3x-y+10=0$
• B. $3x+y-10=0$
• C. $3x+y+10=0$
• D. $x+3y-10=0$

Answer 1

The correct option is B $3x+y-10=0$

Limiting points are $(1,2)$ and $(4,3)$

So, radial axis is the perpendicular bisector of the line joining the limiting points
So, $P=(5/2,5/2)$
Line passing through $(5/2,5/2)$ and having slope $-3$ is
$\Rightarrow 3x+y-10=0$