what do we mean by Feasible and reporting distance ? i read many referance but i don't understand it if anyone have an example or picture to explain it in EIGRP
In EIGRP, the "feasible distance" (FD) is the lowest metric known for a specific route.
By extrapolation, I suspect that the "reporting distance" is whatever metric a neighbor sends, we then add the metric of the link that update came across (or, possibly, the link that is the best link to the next hop; these should ideally be the same, but...).
Once you have a FD, any update whose total metric is the same as the FD for that route will simply add "feasible successors" top the route. Any route with a better metric will update the FD and provide a single successor.
In what context? 'feasible' generally means 'can something be done and what is the impact of doing it?' but reporting distance could mean a thousand things.
Massive edit due to addition of actual context
Now we know you're talking about EIGRP I'm afraid I can't help directly but have found THIS link to a description of these metrics from the Cisco site and THIS one on wikipedia. Sorry I have no better description.