Straight Line And Pair Of Straight Lines Ques 72

  1. A ray of light along $x+\sqrt{3} y=\sqrt{3}$ gets reflected upon reaching $X$-axis, the equation of the reflected ray is

(a) $y=x+\sqrt{3}$

(b) $\sqrt{3} y=x-\sqrt{3}$

(c) $y=\sqrt{3 x}-\sqrt{3}$

(d) $\sqrt{3} y=x-1$

(2013 Main)

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Answer:

Correct Answer: 72.(b)

Solution:

Formula:

A Point and Line:

  1. Take any point $B(0,1)$ on given line.

Equation of $A B$ is

$$ \begin{aligned} & y-0=\frac{-1-0}{0-\sqrt{3}}(x-\sqrt{3}) \\ & \Rightarrow \quad-\sqrt{3} y=-x+\sqrt{3} \\ & \Rightarrow \quad x-\sqrt{3} y=\sqrt{3} \\ & \Rightarrow \quad \sqrt{3} y=x-\sqrt{3} \end{aligned} $$



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