Take triangle ABC. Let A’ be the point in BC that’s twice as far from C as from B.
Similarly, B’ ... on CA twice as far from A as C
C’....on AB 2ce as far from B as A
Connect AA’, BB’, CC’. Prove the middle triangle has 1/7 the area of the original, ABC.
The *only* fact from geometry is that:
The area of a triangle is (1/2)base(height).
This fact will be used freely without mention.
Now I break to shovel 5 million pounds of snow (2 million kg).
Linear algebra FTW!
End
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My pinned tweet (at least for February) also has a correctly threaded version. (The tweet I’m replying to here, isn’t threaded correctly; but I don’t want to delete it because too many people have interacted with it).