A unit radial vector `vecr` makes agles of `a=30^(@)` relative to the x-axis, `beta=60^(@)` relative to the y-axis, and `gamma=90^(@)` relative to the z-axis. The vector `hatr` can be written as :

Options

A. `(1)/(2)hati+sqrt(3)/(2)hatj`
B. `sqrt(3)/(2)hati+(1)/(2)hatj`
C. `sqrt(2)/(3)hati+(1)/sqrt(3)hatj`
D. None of these

Answer

B

Explanation

`vecr= 1 cos alpha hat i+ 1 cos beta hat j+ 1 cos gamma hat k`
`=sqrt(3)/(2)hati+(1)/(2)hatj+0hatk`