Question

If l, m and n are the direction cosines of a vector, then

A) l+m+n=1
B) l^2+m^2+n^2=1
C) l^2+m^2+n^2=0
D) l+m+n=0​

Answer 1

Answer:

B). l²+m²+n² = 1

Explanation:

l = cos(a) = x/r

m = cos(b) = y/r

n = cos(c) = z/r

where r = √x²+y²+z²

where a,b,c are the angles made by the direction vector with x,y,z axes

So, l²+m²+n² = 1 Ans.

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Answer 2

Answer:

ya (option b) is the answer