This short video shows how to prove that the area of the triangle is given by the product of the inradius and the semiperimeter. Here is a longer, alternate version: [ Ссылка ]
Thanks to Colin Wright for suggesting this particular visualization.
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Music in this video:
Prelude No. 9 by Chris Zabriskie is licensed under a Creative Commons Attribution 4.0 license. [ Ссылка ]
Source: [ Ссылка ]
Artist: [ Ссылка ]
![](https://s2.save4k.ru/pic/Ocz2tqt6zz4/maxresdefault.jpg)