The symbol of a triangle is what I used back then to indicate a Major 7th! Be sure to look carefully at the strings that should be muted - they have an "X". For every chord in this lesson, the root note is played by your 1st finger. (The numbers on the strings are your fingers with 1 - first finger and 4 - pinky and the you can guess the other two! I use these chords all the time, enjoy!