Question

one of two forces is the double other and resultant equal to the grater force the angle between them is​

Answer 1

Explanation:

$a = f \: b = \: 2f \\ (2f) {}^{2} = f {}^{2} + (2f) {}^{2} +2 (f)(2f)cos \alpha$

solving the above equation we get

angle between forces 'alpha' is

$\cos \alpha = - 1 \div 4$