same instruction count as my previous solution, but 10 cheaper. arm 3 isn't doing anything horribly complicated and yet has 7 instructions. this is a geometry problem that I wasn't patient enough to solve. this puzzle did give me a reason to care a bit more about TI, and I had fun with it! but I'm not very good at it. shoutouts to zhae, who told me about a dream she had where I got an 8i solve and didn't put spoiler tags around it properly in our discord chat. her dreams believe in my TI skills.