Hi, I know how to draw simple graphs like sinx, cosx, sin2x, cos2x ... etc.

But I am stuck at the following:

1) 2-2cos3x

2) 3-4cos2x (for 0-180)

3) 2-2cosx+2

Could someone tell me the easiest way to draw these on a graph paper?

I know that 3x or 2x in the above means the # of cycles in a 360 range. But I am confused about what to do when 3-4 or 1-2 is added in-front of the functions like in the above examples.