**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