Question

Find the equation of the radical axis of the circle $x^2+y^2-3x-4y+5=0$ and $3x^2+3y^2-7x-8y+11=0$

• A. $x+2y=2$
• B. $y-2x=2$
• C. $x-2y=2$
• D. $y+2x=2$

Answer 1

The correct option is A $x+2y=2$

Given circles may be written as,
$S_1:x^2+y^2-3x-4y+5=0$ and $S_2:x^2+y^2-\frac{7}{3}x-\frac{8}{3}y+\frac{11}{3}=0$
Hence equation of radical axis of these circles is given by,
$S_1-S_2=0\Rightarrow -\frac{2}{3}-\frac{4}{3}y+\frac{4}{3}=0\Rightarrow x+2y-2=0$