not a replace them by a single force

to replace them by a single force

to replace them by a single force through C.G.

to replace them by a couple

magnitude

direction

point of application

all of these

P/2 cos 9/2

IP sin 9/2

2P tan 9/2

IP cos 9/2

forces

independence of forces

dependence of forces

resolution of forces.

the algebraic sum of the resolved parts of the forces in the given direction

the sum of the resolved parts of the forces in the given direction

the difference of the forces multiplied by the cosine of 9

the sum of the forces multiplied by the sine of 9