i have my physics exam tomorrow and i need help understanding this problem because i got this wrong on a previous test

## Homework Statement

Two concurrent forces are acting on a box with a mass of 50.0 kg. One force is 555 N acting at an angle of 140 degrees; the other force is 785 N at an angle of 200 degrees. What third force would have to be added to the situation to produce a state of equilibrium?

## Homework Equations

f= ma i guess... i didnt use it though

## The Attempt at a Solution

555sin(40)-785sin(20) >> V
-555cos(40)-785cos(20) >> H
then i square rooted V^2 + H^2
then i tan^-1(V/H)
and i got some negative funky number

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Use the principle of deficiencies.

Use the principle of deficiencies.
what is that?

$$\sum(F)=0$$

$$\sum(F)=0$$
i probably sound really stupid saying this but.. is that calculus? because if it is i am currently only in algebra II

i probably sound really stupid saying this but.. is that calculus? because if it is i am currently only in algebra II
No that's not calculus that sign (sigma) stands for the sum of all forces.

No that's not calculus that sign (sigma) stands for the sum of all forces.
okay thank you!
i really appreciate it

okay thank you!
i really appreciate it
Did you learn how to use the principle of inertia?