Question

The equation of tangents to the circle $x^2+y^2-6x-6y+9=0$ drawn from the origin are:

• A. $x=y$
• B. $x=0$
• C. $y=2$
• D. $x+y=0$

Answer 1

The correct option is B $x=0$

$e{q}^n$ of pair of tangents is
$S{S}_1=T^2$
$(x^2+y^2-6x-6y+9)\left(9\right)=(-3x-3y+9{)}^2$
$9(x^2+y^2)+9^2-2(3x+3y)9=(3x+3y{)}^2+9^2-2(3x+3y)9$
$\Rightarrow 9x^2+9y^2+18xy=9x^2+9y^2$
$\Rightarrow xy=0$
$\Rightarrow x=0$ or $y=0$