1. Problem: The following coplanar forces pull on a ring: 200 N at 30 degrees, 500N at 80 degrees, 300N at 240 Degrees, and an unknown force. Find the magnitude and direction of the unknown force for the ring if the ring is in equilibrium. 2. Solution(So Far): Using the line 0 Degrees as the x-axis and 90 Degrees as the y-axis I got 351 N for the force (correct according to the book) however I am unable to find what angle it should be at. For the angle I got 71.7 Degrees [The book lists the answer as 71.7+180=351]. After seeing this answer I thought about it and I understand turning it 90 Degrees but why 180 degrees?