A shop sign is attached at its upper edge to a rusty horizontal hinge. The sign remains in equilibrium, hanging at an angle of $25^\circ$ to the vertical, as shown. The sign is a square with side length $52\,\text{cm}$ and has uniform thickness. Its mass is $36\,\text{kg}$. What is the moment of the weight of the sign about the hinge?
- A$39\,\text{N m}$
- B$78\,\text{N m}$
- C$83\,\text{N m}$
- D$92\,\text{N m}$