I have implemented another entity, i.e circle which is again drawn with two points.
Initially I thought to use separate class for the calculations. But seeing that these calculations are not really large and can be accommodated easily, I decided to keep the code in the drgeoDrawingArea.cpp itself.
The circle could be drawn in other ways as well which will be implemented at later stage.
Next I have started implemented ‘arc’ which will be drawn with three points. And the order of selection of these points will decide the arc shape and angles.