Trigonometric functions (Khan Academy) - Opens in a new window
Video tutorials on radians, the unit circle definition of sine, cosine, and tangent, the graphs of sine, cosine, and tangent, basic trigonometric identities, trigonometric values of special angles, the Pythagorean identity, finding amplitude and midline sinusoidal functions from their formulas, period of sinusoidal functions, graphing sinusoidal functions, and constructing sinusoidal functions.