Write the direction cosines of the vectors -2 i + j -5 k . - Vidyadip

Question

Write the direction cosines of the vectors $-2\hat{\text{i}}+\hat{\text{j}}-5\hat{\text{k}}$.

✓

Answer

Given: $-2\hat{\text{i}}+\hat{\text{j}}-5\hat{\text{k}}$
Then, its direction cosines are:
$\frac{-2}{\sqrt{(-2)^2+1^2+(-5)^2}},\frac{1}{\sqrt{(-2)^2+1^2+(-5)^2}},\frac{-5}{\sqrt{(-2)^2+1^2+(-5)^2}}$ or, $\frac{-2}{\sqrt{30}},\frac{1}{\sqrt{30}},\frac{-5}{\sqrt{30}}$

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