Writing Policy class for handling Vector2s and 3s.

I'm finding I have to write a lot of similar code in certain situations for Vector2s and 3s. So, I figured write a generic class that takes a VectorPolicy and does calculations with the appropriate type. The only issue is Vector2s and 3s don't have interfaces backing them. So, I decided to make a policy class that would call the appropriate methods on each. Like so:

 public interface IVectorPolicy<T>
 {
      T Add(T a, T b);
      float Dot(T lhs, T rhs);
 }

That I'd use like so:

 public class Test<T, G> where T : IVectorPolicy, new()
 {
     readonly T vectorPolicy;
 
     public Test()
     {
     vectorPolicy = new T();
     }
 
     public Foo(G vector1, G vector2)
     {
        G g = vectorPolicy.Add(vector1, vector2);
        float dotProduct = vectorPolicy.Dot(g, vector1);
     }
 }

But this causes other issues with G not being known at compile time. As far as I'm aware the compiler cannot figure out the Type of a Generic Type being passed to another Generic Type at compile time. Anyone have any idea how I could work around this?