Question

A ray of light moving parallel to x axis is incident on a parabolic mirror at point p as shown in figure.If the angle of deviation suffered by the ray after reflection is 120° ,the y coordinate of point p is​

Answer 1

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

2

=4AX

Focus is (A,0)(A,0)

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

\Rightarrow x=0,y=-3⇒x=0,y=−3

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

option DD is correct

Explanation: