[79] ヘロンの公式 三角形と内接四角形 両方解説 ブラーマグプタの公式

Contents: Thanks for watching. This video is to give the proof for so-called Heron’s formula and Brahmagupta's formula, which enable us to calculate the areas of given triangle and inscribed quadrangle in a circle respectively simply from the lengths of their sides. These theorem are quite famous and actually useless at the same time, which is all the more why they are famous, I guess. Anyway, the proofs themselves are kinda fun, so just enjoy. 動画の内容：ヘロンの公式の解説動画です。一番有名で無実な公式かもしれませんね。三角形に対してのものはみなさんご存知でしょうが、内接四角形の方はあまり知られていません。ブラーマグプタの公式というやつでしょうか。とはいえその本質と技術は三角形のものと全く同じなので、参考程度に見てください。意外と式変形が楽しいところが見所です。 -------------------------------------------------------------------------------- 主に数学に関することを動画にしています。みんなで面白いことをあーだこーだ言えたらいいなと。 動画に関するアドバイス（声量・ライト・ペン・板書など）や動画にしてほしいことなど何でも受け付けております。むしろください。 連絡等はこちらに→maths.toshi@gmail.com Thanks a ton for visiting here and reading this. Please subscribe this channel and give this video a like if you like it. I usually make videos about mathematics, but any kinds of topics which I find interesting and attractive. All I want to do is just discuss and talk about them, and communicate with people who are into maths, after all. I am afraid to say that I basically speak in Japanese in my videos; however, I am going to try and write things down in the way everyone can comprehend what they are, not without mathematics literacy at least :-). I would appreciate if you gave me any kind of advice ranging from the topics you would like me to bring about to the volume, my handwriting, and the lighting in my videos. Please do not hesitate to leave any comments for this channel growth, and help me to enrich this channel.