I doubt it can work.
ZX80 only uses integer math, no trigonometry, no PLOT.
Hence the question and why there was no answer.
It's far from easy if you want to calculate it.
Of course you can take a circle , convert the content to ZX80 string and print it.
But that's a solution to a different question
![Wink ;)](./images/smilies/icon_e_wink.gif)
Or change the ZX80 ROM to a ZX81 ROM
In theory, there is no difference between theory and practice. But, in practice, there is.