Semi-circular, it is best to stand on the stairs, level by level, with a row of 10 people, and the distance between the fifth person and the sixth person is two or three, so that the formation is better, the sound is easier to spread, and it is heard by everyone present! No stairs can be replaced by tables and chairs! The first row stands, the second row stands on the chair, and the third row stands on the table. The effect is also good! This is how we stand in the chorus. There are 54 of us, standing in five rows. The effect is very good. ~ you can consider using this formation.