Let $A, B$ be two distinct points on the parabola $y^{2}=4 x$. If the axis of the parabola touches a circle of radius $r$ having $A B$ as diameter, the slope of the line $A B$ is

Let

$A, B$ be two distinct points on the parabola

$y^{2}=4 x$ . If the axis of the parabola touches a circle of radius

$r$ having

$A B$ as diameter, the slope of the line

$A B$ is
(A)

$-\frac{1}{r}$
(B)

$\frac{1}{r}$
(C)

$\frac{2}{r}$
(D)

$-\frac{2}{r}$

Ans(C,D)

Let $A, B$ be two distinct points on the parabola $y^{2}=4 x$ . If the axis of the parabola touches a circle of radius $r$ having $A B$ as diameter, the slope of the line $A B$ is