How to find the root of any triad or 7th chord:
- Squash the notes into the same octave, removing any repeated notes if necessary.
- Look at the intervals between adjacent notes. Is one of them a 2nd or 4th? If so, the top of the 2nd or 4th is the root.
- If not, the bottom note is the root.
Note that if you have more than one 2nd or 4th it isn’t a straight triad or 7th chord.