Everything in geometry is built up from simple points. In dynamic geometry, a point can be dragged from its current position to any other location. A line segment is made up of all the points along the path between two points (the endpoints of the segment).
A circle is all the points (“circumference”) that are a certain distance (“radius”) from one point (“center”). Therefore, any line segment from the center point of a circle to its circumference is a radius of the circle and is necessarily the same length as every other radius of that circle. Even if you drag the circle and change its size and the length of its radius, every radius of that circle will again be the same length as every other radius.
For this Challenge, create some points that are constrained to stay on a segment or on a circle.
Decide as a team when you have completed the challenge. Make sure everyone agrees on how to do it.