Ok I have hit a little bumb in the road on my trigonometric function learning. Ok i need to graph the function y=3cos2(x-120degrees)-3, for x is less than or equal to 360degrees but is greater than or equal to -360degrees. Ok so i know the: verticle translation is 3 down the phase shift is 120 to the right amplitude is 3 period is 180 degrees and so i have the horizontal scale at 15degrees. so far so good? Ok now here is the one problem, i do not know if i am to go and as sin grpahs go it starts at highest then to middle then lowest then middle then highest and is finished one wave. Well since my hs=15 each line on graph is 15. now i start on 120 as i have to and herei s my question. When i go down to the middle line which would be -3 would it be on the interval of 150degrees or 135 degrees? Or am i doing it wrong as i thought period meant one full wavelength is 180 degrees so it is making me think i am doing it wrong. Please help if possible.