TUTORIALS:

The Trigonometric Functions
There are two common approaches to the study of trigonometry. In one, the trigonometric
functions are defined as ratios of two sides of a right triangle. In the other,
these functions are defined in terms of a point on the terminal side of an angle in standard
position. We define the six trigonometric functions, sine, cosine,
tangent,
cotangent, secant, and cosecant (abbreviated as sin, cos, etc.), from both viewpoints.
Definition of the Six Trigonometric Functions
Right triangle definitions, where
(see the figure below)
Circular function defiinitions, where θ is any
angle (see the figure below).
The following trigonometric identities are direct consequences of the
definitions (
is the Greek letter phi).
Trigonometric Identities (Note that sin^{2}θ
is used to represent (sin θ)^{2}.)
