Final answer:
The question involves calculating the projection of tension on a line, related to a rigid pole and cross-arm assembly in engineering statics. Specific details, such as angles and positions, are needed to provide an exact answer, which are not provided in the question.
Step-by-step explanation:
The question describes a scenario where a rigid pole and cross-arm assembly are supported by three cables with an induced tension in one of the cables due to the tightening of a turnbuckle. The specific task is to determine the magnitude of the projection of tension (TGF) onto a line defined by points G and F when the tension in cable CD (T) is known to be 1.2 kN. This is a classic statics problem that would involve resolving vector components and applying principles of static equilibrium to find the required tension projection. Unfortunately, the provided information does not contain the necessary details such as the geometry of the assembly and the angles involved to precisely calculate the projection of tension TGF. Therefore, without additional details or a diagram to reference, it's not possible to provide an accurate calculation. However, if given the angles and positions of the cables, one could use trigonometric relationships to calculate TGF.