Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...

A lesson plan where students will interpret the trigonometric functions in terms of the unit circle, graph a sinusoidal function, and use a sinusoidal function to make interpretations in a modeling context.

Provides a detailed explanation of trigonometric functions with examples of reference angles and ratios.

Using similar triangles, a relationship is established between the six trigonometric functions of an angle and simple line segments. These relationships are then confirmed using line segment measurement capabilities of the graphing...

Description and examles of the unit circle angles.

[Free Registration/Login may be required to access all resource tools.] Find all angles on the unit circle matching exact trig ratios. Resource includes examples, videos, and practice problems.

This section explores the relationship between right triangles, circles, and trigonometry. It investigates how a right triangle that is set inside a circle and rotates around the circle is connected to trigonometric functions and their...

This section explores the Pythagorean Identity and how it applies to right triangles set inside unit circles, in terms of sine, cosine, and tangent functions.

Relates the unit circle to the method for finding trig ratios in any of the four quadrants. Demonstrates how the unit circle might be useful.

This site offers a problem and solution to finding all possible slopes for a line tangent to a circle given a particular equation of a circle. Could be an interesting challenge for students.