JEE Main 2025MathematicsStraight LinesMediumMCQ

JEE Main 2025Straight Lines Question with Solution

JEE Main 2025 (8 Apr Shift 2)

Question

A line passing through the point makes an acute angle with the positive x -axis. Let this line be rotated about the point through an angle in the clock-wise direction. If in the new position, the slope of the line is and its distance from the origin is , then the value of is

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Show full solutionCorrect option: A
Correct answer
A4

Step-by-step explanation


$\begin{aligned}
& \mathrm{m}_{\mathrm{PR}}=2-\sqrt{3}=\tan 15^{\circ} \\ & \therefore \frac{\alpha}{2}=15^{\circ} \quad \Rightarrow \alpha=30^{\circ}
\end{aligned}\begin{aligned}
& y=\tan 15^{\circ}(x-a) \\ & y=(2-\sqrt{3})(x-a)
\end{aligned}\perp=\frac{1}{\sqrt{2}}\begin{aligned} & \left|\frac{\sqrt{3} a-2 a}{\sqrt{4+3-4 \sqrt{3}+1}}\right|=\frac{1}{\sqrt{2}} \\ & \frac{|a|(2-\sqrt{3})}{2 \sqrt{(2-\sqrt{3})}}=\frac{1}{\sqrt{2}} \\ & |a|=\frac{\sqrt{2}}{\sqrt{2-\sqrt{3}}}=\sqrt{2}(\sqrt{2+\sqrt{3}}) \\ & a^2=2(2+\sqrt{3}) \\ & 3 a^2 \tan ^2 \alpha-2 \sqrt{3} \\ & 3 \times(4+2 \sqrt{3}) \cdot \frac{1}{3}-2 \sqrt{3}=4\end{aligned}$

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About this question

This is a previous-year question from JEE Main 2025, covering the Straight Lines chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.