AMU Engineering 2019 solved paper Solved Paper

Here in the figure it is shown that a ray right passing through the point Q(1,2) and reflected from a point P(α,0) on X -axis towards points R(5,3)
∴ slope of incident ray (i.e., before reflection)
⇒tan(π−θ)=

0−2

α−1

⇒−tan‌θ=

−2

α−1

⇒tan‌θ=

2

α−1

.......(i)
Similarly, slope of reflected ray
(i.e., after reflection)
⇒tan‌θ=

3

5−α

.......(ii)
From Eq. (i) and (ii), we get
⇒

2

α−1

=

3

5−α

⇒10−2α=3α−3⇒α=13∕5