How to write a circumference algorithm?

Hello. I’m currently Scripting a Horror Game, this uses FOVCircumference calculations, it’s a pretty cool concept, I’d love to share more about it, only this is specific to a type of Game, more specifically it’s mechanics should be using it. I’m new to algorithm, although for me right now it’s tough, every attempt I’ve made goes horribly wrong, I can’t figure out how to draw a Circle below the Characters Rig with the Circumference of the given FOV, can anybody help me?