All cosine functions start off looking like this without applying any transformation:
The steps to graphing cosine waves is identical to graphing sine waves. A summary of steps as explained in the previous video are written below:
(a) Draw two horizontal lines, each at a distance equal to the amplitude a from the x axis.
(b) Draw a vertical line at a distance from the origin equal to the period P. We now have a rectangle of width P and height 2×a.
(c) Subdivide the period P into four equal parts. Label the x axis at these points, and draw vertical lines through them.
(d) Lightly sketch in the sine/cosine curve.
(e) Shift the curve by the amount of the phase shift.