How to calculate circle/circle coordinates?

Question

Mathematics

You need to insert points in random places on the side of the circle. Not inside.
.
ps google couldn't come up with the right query. Offered only inside, but for me that's where the line is.

Answer 1

There is such a thing as trigonometry.
From it (sometimes) it is known that: the
sine is the ordinate of the point (on the unit circle),
and the cosine is the abscissa (of the same point).
Everything is not so gloomy up close :)

Answer 2

Take a spherical coordinate system , fix r, and randomize the angle.
PS
In the comments, they correct that you need to use the polar system , which is obtained from the one I mentioned by throwing out one coordinate.