I'm stuck on the following question:
ABCD is a uniform square lamina with side 4 and mass 8kg. It's hinged at A so that it is free to move in the vertical plane. It is mantained in equilibrium with B vertically below A by a horizontal force acting at C and a vertical force acting at D, each of magnitude F newtons. Find the value of F.
I don't know how to resolve the forces when taking moments at A or if they even need to be resolved since a square has 90 degrees so the forces are penpendicular to the side AB. Can someone help please?