Circumference of a circle

To calculate the circumference of a circle, all you need to know is:
- diameter,
- radius,
- area of ​​a circle,
- the diagonal of the inscribed rectangle,
- the side of the circumscribed square,
- sides and area of an inscribed triangle,
are the area and half-perimeter of the circumscribed triangle,
side of an inscribed regular polygon.
The purpose of this application is the education of cognitive interest in mathematics.