Sine, Cosine and Tangent

The following section introduces the trigonometric functions: sine, cosine, and tangent.

A straight line with an arbitrary length (say 5cm) is drawn at an angle, theta, as measured from a positive x-axis; and the line is separated into an x-component and a y-component.

 

The value of the y-component divided by the length of the line is calculated for each value of angle theta. The resulting graph is called the sine function. This graph is identical for all values of the length of the line.

Similarly, the value of x-component divided by the length of the line is calculated for each value of angle theta. The resulting graph is called the cosine function. This graph is identical for all values of the length of the line.

Also, the value of the y-component divided by the x-component is calculated for each value of angle theta. The resulting graph is called the tangent function. This graph is identical for all values of H (length of the line).

The graphic below shows the cosine function and sine functions as generated from a rotating vector.