These three orbitals, which are identical apart from their orientation in space (and
are not normalized) all lie in the same plane and point toward the corners of an
equilateral triangle.
A linear arrangement of electron pairs requires two hybrid orbitals, and so we
mix an s-orbital with a p-orbital to obtain two sp hybrid orbitals:
These two (unnormalized) sp hybrid orbitals point away from each other at 180
and result in a linear molecule. This is the arrangement in CO2.