One hypothesis about the shape of the universe is that the universe is in the space of Euclidean geometry and flat. In Euclidean geometry, it is assumed that straight lines extend everywhere, planes ...

Everyone learns the number one rule about triangles in high school: the angles of a triangle add up to 180 degrees. But did you know that sometimes they don't? Triangles are much more interesting than ...

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American Most of us learn some amount of Euclidean ...

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As the following graphical construction is easily executed, representing to the eye the figure usually employed for the proof of Napier's rules of the parts of right-angled triangles in spherical ...