We now tackle one of the lesser used triad chords, the augmented chord. This chord tends to be used more in jazz than any other genre due to it's unresolved sound and slight dissonance. Nevertheless, it is a triad chord, and one you should know!
As with all chords, we simply need to learn the formula to be able to build the chord. In the case of the augmented chords, we are taking a major chord are sharpening the 5th note. By sharpening the 5th, you are taking a very 'safe' note and changing it to a much more dissonant note compared to the 1st and 3rd, which creates the unresolved sound of this chord. The formula is the 1st, 3rd & #5th from the major scale. Here is an example in G: