At the end of the 13th century Pope Boniface VIII wanted to commission some paintings for St. Peter’s Cathedral, in Rome, and sent a courier round Italy to find the best painter.
One artist in Florence, named Giotto, just took a sheet of paper and painted a perfect circle on it, freehand.
The Pope gave Giotto the commission. Over six hundred years later, Giotto’s skill is still famous.
Since you’re not Giotto, use another method.
- Have, with your maths kit, a 2p coin (diameter 25.9 mm). That will do for many diagrams.
- Where a diagram calls for a larger circle, or two circles, one larger than the other, it’s useful to get a larger disc. I’ve got some 50mm and 75mm plastic discs, which you can keep with your maths kit, and should help.
- For a larger or more detailed diagram, use compasses.