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

Slide44.JPG

Slide45.JPG


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)

Go Ad-free
Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.