The projections of a vector on the three coordinate axis are $6,-3,2$ respectively. The direction cosines of…
The projections of a vector on the three coordinate axis are $6,-3,2$ respectively. The direction cosines of the vector are
$6,-3,2$
$\frac{6}{5},-\frac{3}{5}, \frac{2}{5}$
$\frac{6}{7},-\frac{3}{7}, \frac{2}{7}$
$-\frac{6}{7},-\frac{3}{7}, \frac{2}{7}$
Solution
Projection of a vector on coordinate axis are $x_2-x_1, y_2-y_1, z_2-z_1$
$
\begin{aligned}
& x_2-x_1=6, y_2-y_1=-3, z_2-z_1=2 \\
& \sqrt{\left(x_2-x_1\right)^2+\left(y_2-y_1\right)^2+\left(z_2-z_1\right)^2}=\sqrt{36+9+4}=7
\end{aligned}
$
The D.C's of the vector are $\frac{6}{7},-\frac{3}{7}, \frac{2}{7}$