The angle subtended by vector `vecA = 4 hati + 3hatj + 12hatk` with the x-axis is :

Options

A. `sin^(-1)((3)/(13))`
B. `sin^(-1)((4)/(13))`
C. `cos^(-1)((4)/(13))`
D. `cos^(-1)((3)/(13))`

Answer

C

Explanation

The angle subtended by the vector A with the X-axis is
`cos theta = (hati*A)/((1)|A|)`
`= (4)/(sqrt(4^(2) + 3^(2) + (12)^(2)) )=(4)/(13)`
`therefore theta = cos^(-1) ((4)/(13))`