A vector a makes `30^(@)` and `b` makes `120^(@)` angle with the `x`-axis. The magnitude of these vectors are 3 unit and 4 unit, respectively. The magnitude of resultant vector is

Options

A. 3 unit
B. 4 unit
C. 5 unit
D. 1 unit

Explanation

(c) The figure shown as described in the question.

According to paralllelogram law of vectors,
`R=sqrt(a^(2)+b^(2)-2ab cos alpha)`
`=sqrt(3^(2)+4^(2)+2xx3xx4 cos 90^(@))=5` units