બે બળોના મૂલ્યોનો સરવાળો 18 N છે.અને 12

$A + B = 18$…(i)

$12 = \sqrt {{A^2} + {B^2} + 2AB\cos \theta } $…(ii)

$\tan \alpha = \frac{{B\sin \theta }}{{A + B\cos \theta }} = \tan 90^\circ $

$⇒$ $\cos \theta = - \frac{A}{B}$…(iii)

By solving (i), (ii) and (iii),

$A = 13\,N$ and $B = 5\,N$