How to make a position orbit around another position for a certain angle

Basically im making a cutting system that would replicate sukunas domain expansion. I want it so there would be many slashes consisting of an origin point of the slash, the length of the slash, and the turning angle.

The upper ball point next to the length is the starting position of the slashes turning angle, and that point will turn around the turning angle to create a slashing effect. But i have no idea how to calculate that.
how i do dis?