Check sibling questions

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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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 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.