The augmented sixth chord in a major key is the same as the chord in the parallel minor key. Below are the French augmented sixth chords for A major and A minor:

In major keys, we must lower the bass of the chord by half a step to obtain an augmented sixth interval. In the case of the German sixth chord (the example is in A major), we must also lower the fifth from the bass:

The German sixth is often spelled enharmonically when resolving to the tonic chord in second inversion. In this case, it would be D#-Eb:

In this case, the chord has several names: the enharmonic German sixth, the doubly augmented fourth sixth, or the Swiss sixth (as proposed by Walter Piston). In theory, it is a second inversion II degree seventh chord.