Wolfram Research
Wolfram Math World: Cosine
Graphs of the cosine function, both 2-dimensional and 3-dimensional. Higher level mathematics applications given, including defining the hyperbolic cosine function, the cosine function as an infinite sum and infinite product, and more.
Clark University
Clark University: Dave's Short Trig Course: Trigonometric Functions
The Clark University site shows and explains the graphs of the six trigonometric functions. It explains how to find an arbitrary angle measurement using trig. Also, it explains that sine and cosine functions are complementary.
BBC
Bbc: Radians and Equations
BBC provides a tutorial that explains how radians are related to degrees and demonstrates how to solve trig equations in radian units. Examples and a practice test are available.
Math Is Fun
Math Is Fun: Graphs of Sine, Cosine and Tangent
Students learn about the graphs of the sine, cosines, and tangent functions. The tutorial consists of notes and examples.
CK-12 Foundation
Ck 12: Trigonometry: Amplitude, Period, and Frequency
[Free Registration/Login may be required to access all resource tools.] Combine calculations for amplitude and period on a sine or cosine graph.
Interactive Mathematics
Interactive Mathematics: Graphs of Sine and Cosine Functions
An interactive graph provides a demonstration to show how the measure of an angle is related to the sine and cosine waves. Topics covered include amplitude and period. Examples allow students to practice the concepts.
Other
Personal Site: Sine and Cosine Do "The Wave"
This personal site provides a great animation of how the sine and cosine waves are formed. It connects the unit circle with the sine and cosine graph.