How to create a pic like this?

Answer 1

[the cyclist]

My recommendation is to look through the Plot Gallery and find something similar to what you are trying to create. The code used to create those plots is available by clicking on the figure. Then you may be able to adapt it to exactly what you want.

If you get stuck, then you could come back here with a more specific question.

[P]

Thank you! But let's see http://www.gooood.hk/_d274957045.htm#userconsent# .I'm wondering how i can create a curved surface to describe the trajectory of the moving side.