xkcd

Title text:

They're continuing to search for a square with the same area as the circle, as efforts to construct one have run into difficulties.

Transcript:

[In a single panel, White Hat, Ponytail, Miss Lenhart, Cueball, and Megan are standing in a field. Ponytail is holding a notebook and taking notes, Miss Lenhart is kneeling and holding her hands on a circular object with the radius marked on it, Cueball is holding a large caliper-like measuring instrument, and Megan is taking a photo with her phone sideways.]

[Caption below the panel:]
Math breakthrough: Dimensional analysts have discovered a real unit circle. Once they measure it, units can finally be added to all our geometry textbooks.

Source: https://xkcd.com/3041

explainxkcd for #3041