Not sure what this question is asking me, when their is no numbers to calculate, can someone please explain this to me
If Cos(x)=m then what is the value of Cos (180-x)?
It's a trigonometric identity.
cos(180 - x) is always the opposite of cos(x).
You could come to that conclusion several ways, but the easiest method is to look at a typical angle Q on a graph and compare it with its supplement (which is defined as 180 - Q), and then you will see why the conclusion is true.