# Welcome to math, where everything is cool if you know how it worksOctober 18, 2018 3:40 PM   Subscribe

The steel balls between the bowls seem terrified!
posted by Splunge at 3:48 PM on October 18, 2018 [1 favorite]

OMG YES, showing this to my math fearing father. See, Dad? See why I like this???
posted by Abehammerb Lincoln at 3:56 PM on October 18, 2018 [1 favorite]

Did...did you just turn the surface area of a sphere into the area under the curve of a sine-wave?
WITCHCRAFT, BLACK MAGIC I SAY!
posted by The Legit Republic of Blanketsburg at 4:04 PM on October 18, 2018 [4 favorites]

Thanks for these. I watched the milling several times. I've never really got math, but things like these make it real. The Sketchup sphere flattening one is so elegant.
posted by unearthed at 4:26 PM on October 18, 2018 [1 favorite]

Procedural symbols drawn by a mechanical plotter that uses a Lamy fountain pen (and Lamy blue ink). I've never heard of a plotter that uses an honest to god fountain pen.
posted by ardgedee at 4:33 PM on October 18, 2018 [3 favorites]

I liked the Lemarchand Configuration solving itself.

“We have such... topologies... to show you.”
posted by GenjiandProust at 5:11 PM on October 18, 2018 [1 favorite]

This doesn't help me with my stupid Calculus homework today.
posted by rhizome at 7:38 PM on October 18, 2018 [3 favorites]

Oh, one of *those* people, huh?

When I was a kid, I liked to take a strip of paper (cut a half-inch off the edge of a sheet of paper), twist one end 180 degrees, and then tape the two ends together. Then I'd walk up to a victim and say "this only has one side". They'd say something like "no way" or "you're nuts". Then I'd give them a pencil and say "draw a line around the middle of one side."

For the big finish? Hand them a pair of scissors and say, "Okay, now cut it along your line."
posted by Twang at 7:46 PM on October 18, 2018 [2 favorites]

my wife teaches math so some high-schoolers are definitely gonna see these.
posted by wellifyouinsist at 9:27 PM on October 18, 2018

OK, math people, what is wrong with this reasoning:

Let's find the surface area of a hemisphere. Taking infinitely many thin slices of the hemisphere, each of which has an area of 2*pi*r, the circumference, times dr, the height, it looks to me like the whole thing is an integral of 2*pi*r, which is, iirc, pi* r^2. Adding that to the other hemisphere, I get a surface area of 2* pi* r^2, which is half of what the correct formula really is. Please hope me!
posted by thelonius at 3:52 PM on October 19, 2018

thelonius: here's an explanation of why that argument doesn't work. The short answer is that the slices don't have a height of dr—it's a more complicated expression than that.
posted by panic at 6:23 PM on October 20, 2018 [1 favorite]

thanks! I was thinking about that earlier today
posted by thelonius at 6:28 PM on October 20, 2018

This is beautiful, thank you.
posted by seyirci at 7:29 AM on October 24, 2018

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