Question

19. f=1.56 Sin is 0-4037 I-56KN -1-5068 So. Cartesian Tepvesentation el vector 0.4041- 151j faeo-feaxo is Correct ansoer a.)

why did we use sin for the Fx and the cos for the Fy ?

Answer 1

because

1S KN

in the given diagram in Right angle $\Delta$ABC

Sin150 = BC/AC  

so BC = AC*sin 150

BC is the force in X direction and AC is the force in given direction

similarly

n Right angle $\Delta$ABC

cos 150 = AB/AC  

so AB = AC*cos150

AB is the force in Y direction and AC is the force in given direction