17kN
Explanation:
The force of 10 kN in the cable and the load of 10 kN both have a component along the crane arm.
The force F exerted by the crane arm on the pulley is the sum of these 2 components.
Component of force in cable along the crane arm = 10 cos 30°
Component of load along the crane arm = 10 cos 30°
Considering the forces on the pulley,
F = 10 cos 30° + 10 cos 30°
Force F = 17.32 kN = 17 kN