Q9 of 45 Page 1

Write the direction cosines of a line equally inclined to the three coordinate axes.

Given: α = β = γ


∴ cos α = cos β = cos γ


∴ l = m = n … (1)


We know that l2 + m2 + n2 = 1


⇒ l2 + l2 + l2 = 1


⇒ 3l2 = 1


⇒ l2 = 1/3



From (1),



∴ Direction cosines are


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