Here are some excellent videos and links on the graphs of circular functions
Video 1
Explains how to determine the equation of a transformed sine function from its graph 
Video 1
Video 2

Video 2
Explains how to determine the equation of a transformed cosine function from its graph 

Video 3
Explains how to graph sine and cosine graphs with several transformations applied 
Video 3

Videos 4, 5 and 6 are just more examples of graphing sine and cosine functions with different transformations. It would be great practice to pause the video, sketch the graph yourself and then confirm that your graph is correct by plaing the video.
Videos 7 and 8 explain how to sketch a tangent function with a horizontal shift. 
Video 4
Video 5
Video 6
Video 7
Video 8

The link to the right goes to a website that gives a very clear demonstration of graphing a complex transformed sine function in clear steps.
