Matt Parker on circles and centres of mass. More links & stuff in full description below ↓↓↓ The man who loved circles: https://www.youtube.com/watch?v=AzmUCL1OHhs Matt's signed book (& extra goodies): http://bit.ly/Matt_Signed Amazon (US): http://bit.ly/Matt_4D_US Amazon (UK): http://bit.ly/Matt_4D_UK Discuss this video on Reddit: http://redd.it/2ftbcl * Although correct, Matt does not use the most elegant method here, introducing more negatives than he would have liked. He apologises. Correction: 45 degrees is equal to pi/4 radians Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile Videos by Brady Haran Brady's videos subreddit: http://www.reddit.com/r/BradyHaran/ Brady's latest videos across all channels: http://www.bradyharanblog.com/ Sign up for (occasional) emails: http://eepurl.com/YdjL9 Numberphile T-Shirts: null Other merchandise: https://store.dftba.com/collections/numberphile