## GeoGebra Tutorial 27 – Animation and Epicycle

This is the 27th tutorial of the GeoGebra Intermediate Tutorial Series. If this is your first time to use GeoGebra, you might want to read the GeoGebra Essentials Series.

In this tutorial, we rotate a circle about the center of another circle tangent to it using the animation feature of GeoGebra. Along the rotating circle, we will also rotate a point on its circumference about its center (see red point in the diagram). The path of this point is called the epicycloid.

If you want to follow this tutorial step-by-step, you can open the GeoGebra window in your browser by clicking here.  You can view the output of this tutorial here. » Read more

## GeoGebra Tutorial 26 – Constructing a Cycloid

This is the 26th tutorial of the GeoGebra Intermediate Tutorial Series. If this is your first time to use GeoGebra, you might want to read the GeoGebra Essentials Series.

A cycloid is the curve defined by the path of a point on the edge of circular wheel as the wheel rolls along a straight line.  In this tutorial, we use GeoGebra to construct a cycloid, the path traced by a rotating circle. In reality, we will not really roll the circle but use mathematics to make it appear is if it is rolling. We will set the amount of rotation to $4 \pi$ but you can choose to increase it later on.

The output of this tutorial is shown above. Move the slider and observe what happens.