Khan Academy Static

The_unit_circle_definition_of_sine_cosine_and_tangent

Learn about the ingenious way in which we define the trigonometric functions for any real number.

Basic_trigonometric_identities

Learn about very useful trigonometric identities that arise by considering different properties of the unit circle definition.

Introduction_to_radians

Learn about radians, which are the official unit of measurement for angles in algebra (in contrast to degrees, which are used in geometry).

The_graphs_of_sine_cosine_and_tangent

Learn how the graphs of y=sin(θ), y=cos(θ), and y=tan(θ) look, using the unit circle definition of the functions.

Trigonometric_values_of_special_angles

Learn how to find the trigonometric values of some special angles without the use of a calculator.

Long_live_Tau

Watch videos by Sal and Vi that discuss the ongoing battle between the more popular Pi (π=3.14..) and its more qualified rival Tau (τ=6.28...).

The_Pythagorean_identity

Prove the Pythagorean trigonometric identity for all real numbers and use it in order to solve problems.