l = m = n = 1 represents the direction cosines of: - Vidyadip

MCQ

l = m = n = 1 represents the direction cosines of:

A
x−axis
B
y−axis
C
z−axis
D
none of these

✓

Answer

none of these

Solution:

Suppose, l, m, n are direction cosines

⟹ 1² + m² + n² = 1

But 1 = m = n = 1

⟹ 3m² = 1

⟹ 1 = m = n = $\frac{1}{\sqrt3}$

which are not direction cosines of either of the three co-ordinate axes.

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