Three types of stages and the stage areas...
A proscenium stage has an audience on ONE SIDE.
A thrust stage has an audience on THREE SIDES. It's "thrust" into the audience. It's diagrammed JUST LIKE THE PROSCENIUM STAGE above.
An arena stage (theater-in-the-round) has an audience on ALL SIDES, and is diagrammed like a compass (N, E, W, S, NE, SE, NW, SW, and C) or the face of a clock (digits 1 through 12 and C).