Even on a fairly simple swept wing there's quite a difference between the mean aerodynamic and geometric chords.
If memory serves me correctly, the values for the BAe Hawk were 1.777m for geometric and about 2.1-2.2m for aerodynamic - interestingly, perhaps, it was the gemoetric chord that was used EVEN for aerodynamic purposes - it is, after all, just an arbitrary reference length.