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A 10 inches long pencil AB with mid point C and a small eraser P are placed on the horizontal top of a table such that PC=√5 inches and angle PCB=…

JEE Main 2021 — Mathematics Trigonometry

2021mcqmedium

A 101010 inches long pencil ABABAB with mid point CCC and a small eraser PPP are placed on the horizontal top of a table such that PC=5PC=\sqrt{5}PC=5​ inches and ∠PCB=tan−1(2)\angle PCB={\mathrm{tan}}^{-1}(2)∠PCB=tan−1(2). The acute angle through which the pencil must be rotated about CCC so that the perpendicular distance between eraser and pencil becomes exactly 111 inch is :

JEE Main 2021 Mathematics, Trigonometric Ratios and Identities — question figure

Official previous-year question

Held on 26 Aug 2021 · Verified 6 Jul 2026.

Options

  1. A

    tan−1(34){\mathrm{tan}}^{-1}(\frac{3}{4})tan−1(43​)

  2. B

    tan−1(12){\mathrm{tan}}^{-1}(\frac{1}{2})tan−1(21​)

  3. C

    tan−1(43){\mathrm{tan}}^{-1}(\frac{4}{3})tan−1(34​)

  4. D

    tan−1(1){\mathrm{tan}}^{-1}(1)tan−1(1)

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