[207] 二直線の平行条件・垂直条件 本質的美しい証明 単位ベクトルと内積の本当の意味と利用

Contents: Thanks for watching. An elegant proof of the conditions of two lines which are parallel or vertical. You might have showed them in an unsophisticated way before, but I here give an elegant way from the perspective of vectors. 場合分けなどしてめんどくさく愚直に証明した経験があるでしょうか？今日それから卒業して大人になりましょう。美しくエレガントな洞察を差し上げます。 -------------------------------------------------------------------------------- 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。 Contact → 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.