The initial circle represents the earth. The triangle that shares the diameter represents the Pyramid of Giza. If the pyramid's angles remained the same and the base grew to equal the Earth's diameter the tip would reach the center of the moon. A circle drawn from the center of the moon, sharing the same origin as the earth will create The Golden Ratio when compared to the square touching each side of the Earth.
Osiris represents the Earth, hence his signature sickle and flail. Isis represents the moon, hence the wings. Horus is the union of both and is represented by the well known symbol of his right eye. On Either side of the moon we have two Perfect Pythagorean Triangles which is also know to symbolize, The Holy Trinity of The Egyptians.