Hi yaseer and all,

Thanks yaseer for your reply with explanation.

Please can you convert or give me code in C#.Net?

Actually i am rotation Line Object.

I can rotate my line on both direction but line is not rotating properly when my mouse rotates.

My Code is:

                                Point actPos = e.GetPosition(MyCanvas);

                                if (oActiveLine != null && sElementName == "Line")
                                {
                                    //Fidning the angle using Triangle theorem.
                                    double a, b, c;
                                    X.X = oActiveLine.Left;
                                    X.Y = oActiveLine.Top;
                                    Y.X = structStartPosition.X;
                                    Y.Y = structStartPosition.Y;
                                    Z.X = actPos.X;
                                    Z.Y = actPos.Y;
                                    b = System.Math.Sqrt(((Y.X - oActiveLine.Left) * (Y.X - oActiveLine.Left)) + ((Y.Y - oActiveLine.Top) * (Y.Y - oActiveLine.Top)));
                                    oActiveLine.Height = System.Math.Sqrt(((actPos.X - oActiveLine.Left) * (actPos.X - oActiveLine.Left)) + ((actPos.Y - oActiveLine.Top) * (actPos.Y - oActiveLine.Top)));
                                    a = System.Math.Sqrt(((Y.X - Z.X) * (Y.X - Z.X)) + ((Y.Y - Z.Y) * (Y.Y - Z.Y)));
                                    c = System.Math.Sqrt(((X.X - actPos.X) * (X.X - actPos.X)) + ((X.Y - actPos.Y) * (X.Y - actPos.Y)));

                                    double angle = System.Math.Acos((b * b + c * c - a * a) / (2 * b * c)) * (180.0 / System.Math.PI);
                                    if (((Z.Y < X.Y) && (Z.X < Y.X)) || ((Z.Y > X.Y) && (Z.X > Y.X)))
                                        oActiveLine.Angle -= angle;
                                    if (((Z.Y < X.Y) && (Z.X > Y.X)) || ((Z.Y > X.Y) && (Z.X < Y.X)))
                                        oActiveLine.Angle += angle;
                                    angle = 0.0;
                                    a = b = c = 0;
                                   
                                }

                                structStartPosition = actPos;