The direction cosines of vector `a=3hati+4hatj+5hatk` in the direction of positive axis of X, is

Options

A. `+-(3)/(sqrt(50))`
B. `(4)/(sqrt(50))`
C. `(3)/(sqrt(50))`
D. `-(4)/(sqrt(50))`

Answer

C

Explanation

`(3)/(sqrt(3^(2)+4^(2)+5^(2)))=(3)/(sqrt(50))`.