Actually it isn't -- the Earth is "squished" a bit by its rotation, but the curvature at the poles is only very slightly less than at the equator or any other point.
At any rate both of us were joking and Cody did derive the Earth's radius of curvature with fairly good precision.
I know, I like joking around about the flat thing (oblate spheroid) because the real flat earthers are fun to joke around with

I believe the outer planets which are much less dense are much flatter at the poles (for example Jupiter and Saturn.)