Final answer:
Trigonal planar shapes can exist even with lone pairs because the lone pairs do not affect the overall shape of the molecule.
Step-by-step explanation:
In chemistry, molecular geometry refers to the three-dimensional arrangement of atoms in a molecule. Trigonal planar shapes can exist even with lone pairs because the lone pairs do not affect the overall shape of the molecule. The molecular geometry is determined by the positions of the nuclei, not the positions of the lone pairs.
For example, in a molecule with a central atom and three surrounding atoms, the electron-pair geometry is trigonal planar. If there are lone pairs on the central atom, they will occupy the available space, but they do not change the overall shape to tetrahedral.