Two force yectors, $F_1=20lb$ and $F_2=40lb,$ are applied at point $O$ as shown in the Figure below. The

direction of the force vectors $F_1$ and $F_2$ are expressed by angle $=30$ and $=45,$ respectively. If the

resultant vector difference vec$(R_d)=$vec$(F_1)-$vec$(F_2)$

a$.$ Sketch the force diagram of the resultant vector difference vec$(R_d)$ based on the parallelogram law concept.

b$.$ Afterward, calculate the magnitude of the resultant vector difference vec$(R_d)$ and the angle between the

resultant vector vec$(R_d)$ and the positive $x$ axis measured in the clockwise direction using the cosines and

sines law.