Question

The resultant of two forces of 3 N and 4 Nis 5 N, then the angle between the forces is -
a) 30°
b) 60°
c) 90°
d) 120°​

Answer 1

$r \: = \sqrt{ {x}^{2} + {y}^{2} + 2xy \cos( \alpha ) } \\ 5 = \sqrt{ {3}^{2} + {4}^{2} + 2 \times 3 \times 4 \cos( \alpha ) } \\ 5 {}^{2} = {3}^{2} + {4}^{2} + 24 \cos( \alpha ) \\ 25 - 9 - 16 = 24 \cos( \alpha) \\ 0 = 24 \cos( \alpha ) \\ \cos( \alpha ) = 0 \\ \alpha = 90 {}^{o}$

Therefore the angle between the two vectors are (c) 90°

Hope this is helpful to you...

Pls mark as brainliest...

Follow me and I'll follow back...