You can measure the area of a polygonal room by taking it apart into triangles and rectangles. You have to split the layout of a room in triangles and rectangles which cover the whole area once. After this you can add all areas together and will get the total area of rooms with even complex layouts.
At following link you will get a template with formulas where you can even transfer the data for the distances into the according cells.
Copy of Template (XLS, 18.50 KB)