The Cross Ratio - Numberphile

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  • Published on Jul 6, 2018

  • One of the most famous free kicks ever taken - but how far from the goal was Brazil's Roberto Carlos? More links & stuff in full description below ↓↓↓ Discussed by Federico Ardila from San Francisco State University. More Federico videos: http://bit.ly/Federico_Numberphile More football/soccer videos by Numberphile: http://bit.ly/Football_Numberphile The goal was scored by Carlos in a 1-1 drawn between France and Brazil at the Stade de Gerland, Lyon, on 3 June 1997 - it was game one of the "1997 Tournoi de France". Goal animation by Pete McPartlan Discuss this video on Brady's subreddit: https://redd.it/8wkcqh Patreon: http://www.patreon.com/numberphile Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science. https://www.simonsfoundation.org/outr... And support from Math For America - https://www.mathforamerica.org/ 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 Videos by Brady Haran Numberphile T-Shirts: https://teespring.com/stores/numberphile 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 Special thanks to these Patreon supporters: Jeremy Buchanan Arjun Chakroborty Jeff Straathof Susan Silver Andy Yana Chernobilsky Christian Cooper Ken Baron Bill Shillito Ben Tony Fadell Turner Lehmbecker Bernd Sing Dr Jubal John Thomas Buckingham Adam Savage Roman Pinchuk James Bissonette john buchan Joshua Davis Steve Crutchfield Jon Padden Jean-Pierre Bergeron Kristo Käärmann Valentin-Eugen Dobrota D Hills Eric Mumford Charles Southerland Arnas Ian George Walker Tracy Parry George Greene Igor Sokolov Alfred Wallace Bodhisattva Debnath


  • people should apologize for using the imperial system, not the metric one

  • Never apologize for using SI units. However you are allowed to use any units you like if you can arguing for it.

  • I really like this. I especially like the quote he reads at the end, I find it humanizes math (with respect to geometry) somehow. Furthermore, everything in this video is completely testable using simple pictures of landscapes that can be measured after the calculations have been made. I just might try this sometime...

  • reading the title i thought it might be about the probability a cross would result in a goal

  • Why don't they show the actual goal, just an animation?

  • This guy definitely has one of the better handwritings of this channel 0001f60c

  • Sam 

    And now this is in wikipedia. So it is officially an internet fact.

  • Wth? People should be apologizing for using the imperial system.

  • Do not apologize for using metric system, apologize for not determining error bars.

  • The reason he apologies for using metric is because the lines on football pitches were defined in yards. You still commonly hear the penalty area be called the "18 yard box" .

  • Is it just me or is it cool and refreshing to see real-world measurements incorporated into one of these

  • Clever way to teach cross ratios.

  • Belgium won because they watched this.


  • I mean, if we're already estimating with a ruler, here's an easier estimation method: Look at the pitch (the stripes) of the field.


  • WTF why didn't they show the goal ?!

  • I just counted the number of stripes cut into the grass. 6+6+little.

  • Quien dice la 16'50!?!?!?!???!?

  • 33.13 meters is about 36.23 yards, so whichever source claimed 35 and used the imperial units was more correct than the metric source 0001f609