how to convert angle to vector in c#

// Don't forget to use the system namespace because Math is in it.
using System;

// radians to vector
new Vector2((float)Math.Cos(radians), (float)Math.Sin(radians));

// degrees to vector
new Vector2((float)Math.Cos(degrees * Math.PI / 180), (float)Math.Sin(degrees * Math.PI / 180));