# Math Help - Resultant Force

1. ## Resultant Force

Forces with magnitudes of 85 pounds and 50 pounds act on a single point. The angle between the forces is 15 degrees. Describe the resultant force.

The answer in the book is: "The resultant force is 113.92 pounds and 5.6 degrees from the 85-pound force."

For the life of me I cannot understand how to obtain this answer though...

2. Is there a diagram to go along with the problem?. That may help.

Try the law of cosines.

$75+\sqrt{85^{2}+50^{2}-2\cdot 85\cdot 50\cdot cos(15)}\approx 113.92$

3. ## Now go solve this thing!

Hey Tek, A parrallelogram is formed from the two added force vectors. The law of cosines is all you need to solve this problem.

(you can solve for a to make your life easier)

So let alpha be equal to 165 (365-15-15 because you need that angle to use this formula) and let b and c be be the sides ajacent to the angle and let b=the resultant vector. I'm pretty sure that's all ya need.

If youneed more help let me Know!