The E-shape augmented barre at the 1st fret, rooted on the low string.
Index finger barres at the 1st fret; the A string is left unsounded
Load F Augmented (Faug) onto an interactive fretboard, hear every note, and build it into a progression.
Play Faug in the Studio →A F Augmented (Faug) chord contains the notes F, A, C#. It is built from the augmented formula 1 - 3 - ♯5, with F as the root.
The augmented triad only has three notes, and in this position the A string would double a tone right next to where it already sounds, thickening the chord exactly where its equal-thirds structure needs to stay clear. Muting it keeps the raised 5th audible instead of buried, which is the whole point of the chord.