Answer:
This a vector addition problem and you need to know the law of cosines and law of sines to solve this problem.
Two vector forces of 80lbs and 70 lbs act on an object at 40 degree angle between them.
The magnitude of the resultant force can be found by applying the law of cosines:
c2 = a2 + b2 - 2abcos140°
where a = 80, b = 70 and c is the resultant force vector you are asked to find
Once you find the magnitude of the resultant force, then you can find the angle it makes wrt the 70lb force using the law of sines:
sinα/a = sin140°/c
where α is the angle opposite side a, or the angle between the resultant and the 70lb vector that you are asked to find. so it would be 140lbs
Step-by-step explanation
