I created an Add-In tool, which insert a feature from Source FC (S) into a Target FC (T). The inserted feature's SHAPE.AREA and SHAPE.LEN values are automatically calculated. In my code, the Area value is also calculated as shown below:
IArea area = f_Target.Shape as IArea;
double d_Area = area.Area;
The results show that d_Area / SHAPE.AREA = 4.10754
I used the Measure Tool and found that the SHAPE.AREA value is CORRECT.
I could not figure out why the ArcObjects code is wrong. Appreciate if you can help with your knowledge.