Submitted by Mr. Donald C. Albin Jr.
Professional Educator
www.donaldalbin.99k.org
Explore the relationship between the unit circle and the trigonometric curves for sine and cosine.
Directions

Move the blue circle around the unit circle. Observe how the two points move along the sine and cosine curves.

Questions to promote inquiry

How can you read the value of the sine function from the unit circle?

How can you read the value of the cosine function from the unit circle?

Compare and contrast the axes of the unit circle and the trigonometric curves.

The tangent is not shown. Name three ways of identifying the tangent from the graphs.

What happens to the trigonometric curves when θ is less than zero or greater than 2π?

The amplitude and period are shown on the graph of the trigonometric curves. Note that the period is measured 'peak-to-peak'. Period and amplitude have physical meaning in the unit circle also. What is the physical meaning of amplitude and period in the unit circle?