Terms
Domain

The set of all possible inputs of a function.
Function

An operation that assigns a correspondence from elements of one set to elements
of another set.
Period

The repeating interval of a periodic function; the period of a function is a
real number.
Periodic Function

A function that repeats itself in regular intervals; it follows this equation:
f (x + c) = f (x), where c is a constant.
Range

The set of all possible outputs of a function.
Reference Angle

The positive acute angle formed between the
terminal side of an angle and the
xaxis.
Rule

The part of a function that dictates the exact correspondence between the
elements of one set and the elements of another set.
Trigonometric Functions

There are six trigonometric functions: Sine, cosine, tangent,
cosecant, secant, and cotangent.
Unit Circle

The circle whose center is at the origin and
whose radius is one.
Cosecant

Given a point P(x, y) on the terminal side of an
angle θ in standard
position, distance d from the
origin, cosecant(θ) = csc(θ) = .

Cosine

Given a point P(x, y) on the terminal side of an
angle θ in standard
position,
distance d from the origin,
cosine(θ) = cos(θ) = .

Cotangent

Given a point P(x, y) on the terminal side of an
angle θ in standard
position,
cotangent(θ) = cot(θ) = .

Secant

Given a point P(x, y) on the terminal side of an
angle θ in standard
position,
distance d from the origin, secant(θ) = sec(θ) = .

Sine

Given a point P(x, y) on the terminal side of an
angle θ in standard
position,
distance d from the origin, sine(θ) = sin(θ) = .

Tangent

Given a point P(x, y) on the terminal side of an
angle θ in standard
position,
tangent(θ) = tan(θ) = .
