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But why is a sphere's surface area four times its shadow?

Duration: 17:01Views: 5.9MLikes: 114.8KDate Created: Dec, 2018

Channel: 3Blue1Brown

Category: Education

Tags: mathematicssphere3 blue 1 brown3 brown 1 blue3b1bthree blue one browngeometry3brown1bluecalculusthree brown one blue

Description: The formula is no mere coincidence. Help fund future projects: patreon.com/3blue1brown An equally valuable form of support is to simply share some of the videos. Special thanks to these supporters: 3b1b.co/sphere-thanks Discussion on Reddit: reddit.com/r/3Blue1Brown/comments/a2gqo0/but_why_is_a_spheres_surface_area_four_times_its The first proof goes back to Greek times, due to Archimedes, who was charmed by the fact that a sphere has 2/3 the volume of a cylinder encompassing it, and 2/3 the surface area as well (if you consider the caps). Check out this video for another beautiful animation of that first proof: youtu.be/KZJw0AYn6_k Calculus series: 3b1b.co/calculus ------------------ These animations are largely made using manim, a scrappy open-source python library: github.com/3b1b/manim If you want to check it out, I feel compelled to warn you that it's not the most well-documented tool, and it has many other quirks you might expect in a library someone wrote with only their own use in mind. Music by Vincent Rubinetti. Download the music on Bandcamp: vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown Stream the music on Spotify: open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u If you want to contribute translated subtitles or to help review those that have already been made by others and need approval, you can click the gear icon in the video and go to subtitles/cc, then "add subtitles/cc". I really appreciate those who do this, as it helps make the lessons accessible to more people. ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe: 3b1b.co/subscribe Various social media stuffs: Website: 3blue1brown.com Twitter: twitter.com/3blue1brown Reddit: reddit.com/r/3blue1brown Instagram: instagram.com/3blue1brown_animations Patreon: patreon.com/3blue1brown Facebook: facebook.com/3blue1brown 0:00 - High-level idea 2:23 - The details 9:12 - Limit to a smooth surface 11:20 - The second proof 15:15 - A more general shadow fact.

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