Answer
The magnitude of the resultant force is 209 N
Work Step by Step
Let $a = 142~N$
Let $b = 215~N$
Let angle $\theta = 112^{\circ}$
We can use the parallelogram rule to find $c$, the magnitude of the resultant force:
$c = \sqrt{a^2+b^2+2ab~cos~\theta}$
$c = \sqrt{(142~N)^2+(215~N)^2+(2)(142~N)(215~N)~cos~112^{\circ}}$
$c = \sqrt{43515.5~N^2}$
$c = 209~N$
The magnitude of the resultant force is 209 N