Degree:
A degree is a unit of angle measurement equal to 1/360 of a circle’s circumference.

Radian:
A radian is a unit of angle measurement that is the ratio of the circle arc cut off by an angle to the central angle.

Sine:
Sine on a unit circle is the “y” coordinate for any intersection between a standard angle and the circle.

Cosine:
Cosine on a unit circle is the “x” coordinate for any intersection between a standard angle and the circle.

Tangent:
The ratio of sine to cosine or, in a right triangle, is the ratio of the length of the opposite side to the length of the adjacent side.

Reference Angle:
A reference angle is the angle between 0 and 90 made with the x axis.

Form of a Trigonometric Function:
Trigonometric functions take the form where A,B, C, and D are coefficients that change the characteristics of that trigonometric function.

Graphs of Trigonometric Functions: 
Graphs may be affected wildly as follows:
Stretching or compressing it along the x-axis
Stretching or compressing it along the y-axis
Moving it up or down along the y-axis

Trigonometry is an important branch of mathematics that is important to learn so advanced Calculus principles can be covered. The measure of angles using radians and degrees is covered with the help of examples.  Converting degree measure to radian measure is performed using the fact that 180 degrees equals to pi.

The trigonometric functions used in a Calculus course and their graphs are shown with the use of examples and graphs. The Reference Angle Theorem is used in conjunction with basic trigonometric identities so simplification of trigonometric expressions can be performed. The sine and cosine functions are defined in relation to the unit circle and special right triangles.

Specific Tutorial Features:

• Examples are given to show the properties of trigonometric functions.
  
• The concept of measuring angles is covered in some examples.
  
• Step by step explanation of how degrees can be converted to radians and vice versa.

Series Features:

• Concept map showing inter-connections of new concepts in this tutorial and those previously introduced.
  
• Definition slides introduce terms as they are needed.
  
• Visual representation of concepts
  
• Animated examples—worked out step by step
  
• A concise summary is given at the conclusion of the tutorial.

Angles and their measures
  Definition of angles 
  Definition of radians
  Degrees and radians and how do we compare them to each other 
  Sine and cosine functions
  Definition of sine and cosine functions
  The tangent function
    The definition of a tangent function
    Reciprocal trigonometric functions
     The definition of reciprocal trigonometric functions
  Trigonometric Identities
Graphs of the Trigonometric Functions used in Calculus
  Definition of the form of a trigonometric function used in Calculus