You probably have an intuitive idea of what a circle is: the shape of a basketball hoop, a wheel or a quarter. You may even remember from high school that the radius is any straight line that starts ...

Download and open circle.html to explore an interactive unit circle. Drag the point around the edge of the circle to change the angle and interact with the unit circle. Special angles (30°, 45°, 60°) ...

The trig tour model tracks the angle and trigonometry evaluations for each of the functions sin, cos, and tan. It can be restricted to 'special angles', angles which result in 'neat' trigonometric ...