Question

The direction cosines of the vector a = (-2i + j - 5k) are

A. -2, 1, -5

B. 1/3, -1/6, -5/6

C. 2/√30, 1/√30, 5/√30

D. -2/√30, 1/√30, -5/√30

Answer 1

Answer is : D. -2/√30, 1/√30, -5/√30

Formula to be used – The direction cosines of a vector ai + bj + ck is given by

Hence, the direction cosines of the vector -2i + j - 5k is given by