A vector of magnitude units has direction cosines and

MATHEMATICS · Single correct · CBSE · Mathematics · Three-Dimensional Geometry · Three-Dimensional Geometry

Problem

A vector of magnitude

15

units has direction cosines

l=-\dfrac{2}{3}

and

m=\dfrac{1}{3}

. If it makes an acute angle with the

z

-axis, which of the following vectors satisfies these conditions? (a)

-10\hat{i}+5\hat{j}-10\hat{k}

(b)

-10\hat{i}+10\hat{j}+5\hat{k}

(c)

-5\hat{i}+10\hat{j}+10\hat{k}

(d)

-10\hat{i}+5\hat{j}+10\hat{k}