AAA Math
Aaa Math: Circumference of a Circle
Calculating the circumference or perimeter of a circle has gotten easier with this formula and practice for finding the circumference.
Mathigon
Mathigon: Geometry: Circle and Pi: Conic Sections
The circle is one of four different shapes which can be created using "slices" through a cone, a 3-dimensional solid that has a circular base joined to a single point (called the vertex) by a curved side. If you tilt a cone, you get an...