Question 18 - CBSE Class 12 Sample Paper for 2024 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Last updated at Feb. 10, 2025 by Teachoo

If the direction cosines of a line are ⟨1/c,1/c,1/c⟩, then

(a) 0<c<1 (b) c>2

(c) c=±√2 (d) c=±√3

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Transcript

Given direction cosines of the line are 𝑙 = 1/𝑐 , m = 1/𝑐 and n = 1/𝑐 We know that 𝒍^𝟐 + 𝒎^𝟐 + 𝒏^𝟐 = 1 (1/𝑐)^2 +(1/𝑐)^2+ (1/𝑐)^2 = 1 3 (1/𝑐)^2 = 1 (𝟏/𝒄)^𝟐= 𝟏/𝟑 1/𝑐 = ±√(1/3) 1/𝑐 = ± 1/√3 c = ± √𝟑 So, the correct answer is (d)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 15 years. He provides courses for Maths, Science and Computer Science at Teachoo

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