How to draw a partial circle?

I am mainly trying to use Vectornator for math notes and there are a few things I cannot figure out how to do.

  1. I need to draw an arc (partial circle) with specific radius. I can draw a full circle no problem, but I can’t figure out how to have only, say 20 degrees do the circle. Something similar to this Circles, Ellipses and Arcs — Inkscape Beginners' Guide 1.0 documentation
  2. i would like to have the circle expand from the middle like the pentagone shape do. Currently the opposite node serves as the anchor. It would be ideal if I could expand from the middle.
  3. I would really love to render latex. Math is so much easier to write in latex. Eventually I want to export the whole thing as an SVG file to embed it into markdown notes.

Thanks for your help