How can i find areas of irregular figures in auto CAD. ?

Make the figure a closed polygon. Use the pedit command and window the figure to convert all the lines and arcs to polylines. If it doesn't work, that means you have open or overlapped intersections. It can become a real pain to try and hunt down a very small gap or overlap. You might want to just go to another layer and trace it with a polyline. It must be closed for the area function to work.