Well, i gave you the Ha'tak.
Cheops Class is what is labeled as Ha'Tak, delete the one named Ha'tak(cheops), and make a 4 sided pyramid for the normal Ha'Tak.

:S I'm getting multiple theories.
We'll go with these names:
Four sided: Pyramid Ship
Three sided: Cheops Class "Ha'tak" Mothership

To throw more wood into the discussion of cheops/ha'tak.
Of note, the actual Cheops Pyramid is 4 sided.