9.24.3 Can you answer these questions?

9.24.3.1 Draw closed curve path using tikz

https://tex.stackexchange.com/landing/r/digest?cta=question&id=682054

How to draw some arbitrary closed curve path using tikz? I find it hard to control the curves in tikz. 
Can anyone give an example code that draws the figure below? 
[tikz-pgf]
 

asked by Liu Zhiyu https://tex.stackexchange.com/landing/r/digest?cta=user&id=255246 Score of 1

9.24.3.2 Visualize connectivity of a document's cross referencing

https://tex.stackexchange.com/landing/r/digest?cta=question&id=682083

Easy management of cross-referencing with \label and \ref is a very handy basic component of most TeXing. 
However, I am wondering if there are any tools out there to visualize the connectivity of a ... 
[cross-referencing]
 

asked by Prunus Persica https://tex.stackexchange.com/landing/r/digest?cta=user&id=159893 Score of 1

9.24.3.3 Drawing affine cone on overleaf

https://tex.stackexchange.com/landing/r/digest?cta=question&id=682051

I do not have that much experience with plotting in LaTex and have no idea how/where to start plotting the following image: 
I would really appreciate some help, thank you! 
[tikz-3dplot]
 

asked by 0hliva https://tex.stackexchange.com/landing/r/digest?cta=user&id=294533 Score of 1