Does a hole in a heated aluminum plate expand or contract?

[hms.tech]

Homework Statement

This is a question from my physics book, i don't understand its solution.

Consider a square hole in an aluminum plate (2D) . If this block is heated,
will this hole become smaller or larger ?

Homework Equations

δL/L = β*δT

The Attempt at a Solution

As each of the side of the block expands (some a lttle, while the longer sides more) thus the area decreases.

But, the answer as given by the book is that the area would increase.
Can anyone help me understand this ?

 

[Doc Al]

All linear dimensions will expand by the same factor, including the hole.