Based on the order of the notes from lowest to highest pitch, the triad above is in first inversion.
In a triad, there are three notes stacked on top of each other, and the position of the notes determines the inversion of the triad. In a first inversion triad, the bottom note of the triad is not the root note, but rather the third of the chord.
In the example given, the bottom note is an E, which is the third of the chord. The middle note is a G, which is the fifth of the chord, and the top note is a C, which is the root of the chord. Therefore, the triad is in first inversion.
