I have made a call on this thread. I will assume that by "oval" means ellipse. Further, this is not a homework question. Until the OP checks back in there is not really much more to be said.
The formula I provided is for the perimeter of an ellipse. The precise method, which may well be in fact the basis for the name Elliptic Intergral, is beyond fundamental math and may be best done numerially. Thus it may provide the basis for a broader dissussion of an interesting topic.