C # - Rotating and Centering an Image

I have an image that I want to rotate clockwise by a specified number of degrees. I don't want to crop anything, so I calculate the width and height of the new image based on the specified rotation (for example, a 45 degree rotation requires a taller and wider image.

//Calculate required size of new image
GraphicsPath path = new GraphicsPath();
path.AddRectangle(new RectangleF(0f, 0f, bmpSource.Width, bmpSource.Height));
Matrix matrix = new Matrix();
matrix.Rotate(iRotationDegrees);
RectangleF rctNewSize = path.GetBounds(matrix);

//Create new image
Bitmap bmpRotated = new Bitmap(Convert.ToInt32(rctNewSize.Width), Convert.ToInt32(rctNewSize.Height));
using (Graphics g = Graphics.FromImage(bmpRotated))
{    
    //Set rotation point to center of image
    g.TranslateTransform(bmpRotated.Width / 2, 0);
    g.RotateTransform(iRotationDegrees);

    //Draw the rotated image on the bitmap
    g.DrawImageUnscaled(bmpSource, 0,0); 
}

      

        
        
        
      

    

With a 45 degree angle, when I set the TranslateTransform to bmpRotated.Width / 2,0, the rotated image is not quite horizontally centered, and the bottom left corner is slightly cut off.

I am missing some math that correctly calculates the appropriate dx / dy values ​​to go to TranslateTransform.