it is basically like this:
This basically means that, cos(x), can be both positive and negative.
So, its like doing two questions in one. You have to solve for both the positive values and the negative values.
So solve for:
and solve for:
So, from each you will get two values in the range of 0 to 360 degrees.
And thus you will have a total of 4 values:
will give you: 30 and (360-30)=330
and
will give you:
150 and 210.
220 is wrong by the way.