The magnitude and direction of two forces acting on an object are 100 pounds, S79degreesE, and 60 pounds N68degreesE, respectively. Find the magnitude, to the nearest tenth of a pound, and the direction angle, to the nearest tenth of a degree, of the resultant force.

2 answers

find the N-S and E-W components of the two forces

add the corresponding components to find the components of the resultant
The angles are referenced to the Y-axis. so we'll assume CW rotation from +Y-axis.
F1 = 100Lbs[79o] E. of S. = 180-79 = 101o CW,
F2 = 60Lbs[68o] E. of N. = 68o CW.

Fr = 100[101o] + 60[68o] = Resultant force,
X = 100*sin101 + 60*sin68 = 153.8 Lbs.
Y = 100*Cos101 + 60*Cos68 = 3.4 Lbs.
(Fr )^2 = X^2 + Y^2 = 23,666,
Fr = 153.84 Lbs. = Resultant force.
Tan A = X/Y For CW rotation.