A method to create a rotated dimension using the AutoCAD .net API
protected void drawDimensions(Point3d dimensionPoint, Point3d point1, Point3d point2, double rotation)
{
using (Transaction tr = db.TransactionManager.StartTransaction())
{
BlockTable blockTable = tr.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
BlockTableRecord modelSpace = tr.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;