If l, l, l are direction cosines of a line, then l = ___________________.

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Solution

Since direction cosines of a line are l, l, l
i.e. l = l, m = l and n = l is given
Since l²+ m² + n² = 1
i.e. l² + l² + l² = 1
i.e. 3l²= 1
i.e. l²= $\frac{1}{3}$
i.e. $l = \pm \frac{1}{\sqrt{3}}$

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If l, l, l are direction cosines of a line, then l = ___________________.

Since direction cosines of a line are l, l, l i.e. l = l, m = l and n = l is given Since l2 + m2 + n2 = 1 i.e. l2 + l2 + l2 = 1 i.e. 3l2 = 1 i.e. l2 = 13 i.e. l=±13

Since direction cosines of a line are l, l, l
i.e. l = l, m = l and n = l is given
Since l²+ m² + n² = 1
i.e. l² + l² + l² = 1
i.e. 3l²= 1
i.e. l²= $\frac{1}{3}$
i.e. $l = \pm \frac{1}{\sqrt{3}}$