• Multihedra [he/him]
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    edit-2
    4 years ago

    This reminds me of a very beautiful result in spherical geometry, called Girard’s Theorem:

    On the unit sphere, a spherical triangle with angles A, B, and C has area A + B + C - π.

    The standard proof involves looking at a diagram, and it’s extremely pleasant once you digest it all. I remember being very proud to recreate the diagram and get it all sorted out in my head.

    Here’s a nice little intro on the topic: https://www.math.csi.cuny.edu/abhijit/623/spherical-triangle.pdf