Spatial functionality in SQL Server is provided by two DLL libraries - Microsoft.SqlServer.Types.dll (managed) and SqlServerSpatial.dll (unmanaged). Import Microsoft.SqlServer.Types.dll into your C# project and you can use the SqlGeography/SqlGeometry
type in exactly the same way as the geography/geometry type within SQL Server. So your example above would become i.e.
SqlGeometry geom = SqlGeometry.STGeomFromText(new SqlChars("POLYGON((3 -6, 8 -3, 8 2, 2 5, -2 0, 3 -6))"), 4326);
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