As shown in the diagram, two forces act on an object. the forces have magnitudes f1 = 5.7 n and f2 = 1.9 n. what third force will cause the object to be in equilibrium?

3.8 n at 108° counterclockwise from
f1->

6.3 n at 162° counterclockwise from
f1->

3.8 n at 162° counterclockwise from
f1->

6.3 n at 108° counterclockwise from
f1->

Second option 6.3 N at 162° counterclockwise from  

F1->

Explanation:

Observe the attached image. We must calculate the sum of all the forces in the direction x and in the direction y and equal the sum of the forces to 0.

For the address x we have:

For the address and we have:

The forces and are known

We have 2 unknowns ( and b) and we have 2 equations.

Now we clear from the second equation and introduce it into the first equation.

Then

Then we find the value of

Finally the answer is 6.3 N at 162° counterclockwise from  

F1->