Verified Solution • 2025–26 Session moderate

QJEEM21Maa6de: JEE Main 2021 Mathematics - Class 12 JEEM21Maa6de Solution: A 10 inches long pencil AB with mid point C and a small eraser…

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 ∠PCB = tan-1(2). The acute angle through which the pencil must be rotated about C so that the perpendicular distance between eraser and pencil becomes exactly 1 inch is :

JEE Main 2021 (Online) 26th August Evening Shift Mathematics - Height and Distance Question 13 English

Multiple Choice Options

  • A tan−1(34)
  • B tan−1(1)
  • C tan−1(43)
  • D tan−1(12)

Step-by-Step Verified Solution


From figure,

sin⁡β=15

∴ tan⁡β=12

tan⁡(α+β)=2

tan⁡α+tan⁡β)1−tan⁡α.tan⁡β=2

tan⁡α+121−tan⁡α(12)=2

tan⁡α=34

α=tan−1(34)JEE Main 2021 (Online) 26th August Evening Shift Mathematics - Height and Distance Question 13 English Explanation

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