Use
View attachment 44706 for area of a circle since 95% of the time they are going to give diameters and not radius
Most of the time if they give you a number in the question expect to use it to work out the answer (or it may lead you to a easier working)
Write any relevant working down, that includes the formulas in the first line and free body diagrams. Also helpful to write the values given in the question matching the variable it goes into at the side to make it clear (you are also giving relevant working so that's probably 1 mark)
Use SI units
If they didnt give any lengths for truss questions assume each side is one unit (more common for equilateral triangle ones)