Question

If the d.c's of a line are $\left(\frac{1}{c},\frac{1}{c},\frac{1}{c}\right)$ , find c.

Answer 1

Consider the problem

As we know

Sum of square of direction ratios is equal to $1$.

Therefore,

$\frac{1}{c^2}+\frac{1}{c^2}+\frac{1}{c^2}=1$

$3\frac{1}{c^2}=1$

$c^2=3$

$c=\pm \sqrt{3}$

So, the value of $c=\pm \sqrt{3}$