Question

Q#02: Two vectors have magnitudes 4 and 5 units. The angle
between them is 30 taking the first vector along X-axis. Calculate
the magnitude and the direction of the resultant.(1997)​

Answer 1

Answer:

To solve questions like this we can use

$r = \sqrt{ {a}^{2} + {b}^{2} + 2ab \cos( \alpha ) }$

Then let's solve the question

$r = \sqrt{ {a}^{2} + {b}^{2} + 2ab \cos( \alpha ) } \\ \\ = \sqrt{ {4}^{2} + {5}^{2} + 2(4 \times 5) \cos(30) } \\ = 8.69$