Getting "trendline" information from excel?

I have a bunch of excel spread sheets that have graphs in them. I need to do some further processing in matlab that involves getting some information from those graphs. I know how to import that data in the non-graphical sheets, but what I can't figure out how to get (or even if it's possible) is the trendlines that have been created in the graphs. I can easily recreate them but I

a) don't always know the order of the fit (they're all either linear or polynomial) and

b) how may trendlines might be present.

Are there automatable ways to solve a and b?