The angle made by the vector `4hati - 3hatj + 5hatk` with z-axis is :

Options

A. `30^(@)`
B. `45^(@)`
C. `90^(@)`
D. `120^(@)`

Answer

B

Explanation

`cos theta_(z)= R_(z)//R`
`" "cos theta= (5)/sqrt((3)^(2)+ (4)^(2) +(5)^(2))=(5)/(5sqrt(3))=(1)/(sqrt(2))`
`" "cos theta= 45^(@)`