Try this old example of finding the net force of three forces at different angles.

https://www.thephysicsaviary.com/Physics/APPrograms/NetForceHard/index.html

Almost like a Quadrant-tester for cell F7:

=IF(AND(D7>0,E7>0),1,IF(AND(D7<0,E7>0),2,IF(AND(D7<0,E7<0),3,IF(E7=0,0,4))))

Updated formula for the resultant angle in cell C7:

=IF(F7=0,0,IF(OR(F7 = 2, F7 = 3), 180 + DEGREES(ATAN(E7/D7)), IF(F7=4, 360 + DEGREES(ATAN(E7/D7)), DEGREES(ATAN(E7/D7)))))