Consider the forces in the two diagrams above. Notice how the angles are important in both cases.

Figure 3:

Clockwise moment about P = 3 x 15 = 45 Nm

Anticlockwise moment = 45 = Tcos 35 x 1.6

Therefore: T = 34.3 N

Figure 4:

Wx2cos60 = 500x3.5cos60

Therefore W = 875 N and this is independent of the angle!