# A ray of light coming from the point (1,2) is reflected at a point A on the x-axis and then passes through the point (5,3). What are the co-ordinates of point A?

siddharth gupta
28 Points
10 years ago
Assume the x-axis to be a  mirror.
take the image of (1,2) in x-axis i.e(1,-2).
as we know that reflected ray when extended back passes through the image of a point on incident ray i.e reflected ray passes through (1,-2) and (5,3).
...from two point form eqn of refl.ray=5x-4y-13=0.
put y=0 ...point of incidence=(13/5,0).
with regards
SIDDHARTH GUPTA
Arun Kumar IIT Delhi
10 years ago
Hello
$\\ tan(\theta)={2 \over 1-x} \\tan(\pi -\theta)={3 \over 5-x}=-tan(\theta)=-{2 \over 1-x} \\3x-3=5-x \\=>4x=8 \\=>x=2$
Thanks & Regards
Arun Kumar
Btech, IIT Delhi
Harsh
34 Points
7 years ago

Assume the x-axis to be a  mirror.
take the image of (1,2) in x-axis i.e(1,-2).
as we know that reflected ray when extended back passes through the image of a point on incident ray i.e reflected ray passes through (1,-2) and (5,3).
...from two point form eqn of refl.ray=5x-4y-13=0.
put y=0 ...point of incidence=(13/5,0).
with regards
Harsh panwar
IIT ROORKEE
AIR 55
Yash sharma
24 Points
6 years ago
Assume the x-axis to be a mirror.take the image of (1,2) in x-axis i.e(1,-2).as we know that reflected ray when extended back passes through the image of a point on incident ray i.e reflected ray passes through (1,-2) and (5,3)....from two point form eqn of refl.ray=5x-4y-13=0.put y=0 ...point of incidence=(13/5,0) Aman bansal AIR1
ankit singh