How to Draw Polygon inside circle and calculate its area?

I want to know how to create polygons inside circle and calculate its area, just like the image below:

GMT symbol sizes are determined by the circumscribed circle. See image in GMT plot manual (not to be confused with the GMT.jl plot manual)

@joa-quim there is a problem here:

I can’t add or use GMT package. I use Julia-1.7.3

Capture d’écran_2022-07-08_18-11-06

I’m afraid you are suffering from the libstd++ problem discussed here and while #45582 is not solved, your option is to install GMT with a package manager or build it yourself (not difficult). See general instructions for Linux here