A mass of 50 Kg is suspended from the top in of the pole that is inclined 40 degrees to the vertical. the end of the pole is supported by a wire that is making an angle of 75 degrees with the pole.
What is the tension in the wire?
http://img833.imageshack.us/img833/1038/diagramxf.png
The moment of a force about a point is the product of the force and the perpendicular distance from the point to the line of the force. When a system is in equilibrium the sum of clockwise moments = the sum of anticlockwise moments