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# Can a vector have direction angles $45^{\circ}, 60^{\circ}, 120^{\circ}$?

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• If $l, m , n$ are the d.c.s of a vector, then $l^2+m^2+n^2=1$
$\cos^245^{\circ}+\cos^260^{\circ}+\cos^2120^{\circ}= \large\frac{1}{2}+\large\frac{1}{4}+\large\frac{1}{4}=1$
$l^2+m^2+n^2=1.$ A vector can have $45^{\circ}, 60^{\circ}, 120^{\circ}$ as direction angles.

edited Jun 24, 2013

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