The Thrilling Adventures of Gabriel, a protractor, and elliptic geometry!

Gabriel Y. measuring the interior angles of a triangle that's been drawn on the surface of a sphere.

In the snapshot above, Gabriel Y. is tackling a quiz question pertaining to the final installment of our reading of The Thrilling Adventures of Lovelace and Babbage.

It’s all well and good to be told or to read that the interior angles of a triangle drawn on the surface of a sphere sum to more than 180° but the real fun is in confirming it with a not-quite-sufficiently-flexible plastic protractor!