Eric is master of illusions! It will show you how to create an optical illusion to draw straight lines that form a curve. It's not magic ... it's mathematical! The pedagogical side:This segment describes the geometry of linear drawings. To create a linear drawing, it is about connecting points on lines or curves with straight lines. There are also linear designs when connecting the lines on a piece of cardboard with wire and nails, which is called wire and nails craftsmanship. The latter gives good results, because when straight lines meet and form an angle, it seems to create a curve with straight lines. The more we divide the two original lines, the more the curve is gradual.