You will need
  • A ruler and a pencil
To find the center of the circle, it is necessary first to inscribe it in a square. That is, all sides of the quadrilateral have to touch the circle. You could do this with a ruler four straight lines.
Now connect the two diagonally opposite corner. Ensure that the line broke the corner of the square into two equal parts. Connect direct to all 4 corners of a square.
The intersection of data and direct will be the center of the circle.
Another piece that can help you determine the center of the circle is a right triangle. It also needs to fit into the circle. And then divide opposite the right angle side in half. The middle of the hypotenuse will be the center of the circle.