Question

A ray of light moving parallel to the $x-$ axis gets reflected from a parabolic mirror whose equation is ${(y+3)}^2=4(x+1)$. After reflection, the ray must pass through the point

• A. $(4,-1)$
• B. $(0,1)$
• C. $(-1,-3)$
• D. None of these

Answer 1

Answer: (D)

None of these

Given parabola is ${(y+3)}^2=4(x+1)$

The ray after reflection will pass through the focus of the parabola

Comparing with the standard equation $Y^2=4AX$

Focus is $(A,0)$

$x+1=1,y+3=0$

$\Rightarrow x=0,y=-3$

So the ray always passes through the point $(0,-3)$

option $D$ is correct