Singular or plural: "The figure(s) in the center and on the right show that..."

Question

In a paper I'm writing, there are three figures: one on the left, one in the center and one on the right. I want to say something about the one in the center and the one on the right. Should I use the singular or the plural form of the word figure in this sentence?

The figure(s) in the center and on the right show that...

I had assumed I should use the plural form. A native speaker said I should use the singular. If both usages sound awkward, I would also appreciate suggestions for alternatives.

Answer 1

I think you can use singular only if you repeat the figure, as follows:

The figure in the center and the figure on the right show that ...

To indicate how the aforementioned parses:

[The figure in the center] and [the figure on the right] show that ...

You can use plural by not repeating the figure:

The figures in the center and on the right show that ...

Which parses to:

The figures [in the center and on the right] show that ...

Answer 2

If you are referring to two different figures at once (both the right and the center), you should refer to them as figures. If you say

The figure in the center and on the right

it sounds like you are referring to a single object that is both in the center and on the right. To maintain the verb agreement with the plural subject, make sure to use show.