4 поворота

*

Сложность: 

Квадрат повёрнут 4 раза, каждый поворот на 90 градусов. Оказалось, что эти четыре поворота можно заменить одним и также на 90 градусов. Как это можно сделать?

Решение

Повернём квадрат сначала вокруг диагонали AC на 180° (или два раза на 90°):

В результате вершины B и D поменяются местами:

Теперь повернём квадрат на 180° вокруг стороны AB:

В результате квадрат примет следующее положение:

Очевидно, что точно такой же результат получился бы, если бы мы повернули квадрат один раз на 90° по часовой стрелке вокруг вершины A (в плоскости квадрата).




Комментарии

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Lynne, I love the straoge area behind the screen door! We are trying to figure out how to convert a walk-in guest room closet into a storage area that has shelves around 3 walls like yours. So glad you posted that photo! I think the screen door is such a great idea. Dianne

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More important than teaching our children money management is to teach our children what it is we actually use for money,how it’s created and put into ciarulction and how that affects our lives.

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Thank you for your wonderful posts! I enjoy them each day. As Lent apepoachrs, I too try to find what I can take hold of in my life, but believe that the true meaning if Lent is self denial as you mentioned, and that should never be tossed aside. Self denial brings us much closer to Jesus than this culture wants to accept!

Hey, I have the same ‘mix ma2e8r&#ts17; as you! I agree, there is nothing more precious than a gift from the heart.The one my brother gave me is priceless. I am also working on being more patient, loving and kind in my daily life. I think that’s a gift that keeps on giving. Merry Christmas to you, Pegolicious!

: c’est dommage que l’on ne puisse pas devenir végétarien :la morale n’est pas là, mais il est certainement dommage que l’on ne puisse devenir nos propres sacrificateur; en france, et d’autres pays, les personnes sont de moins en moins présentes lorsqu’il s’agit de sacrifier pour la cause d&rAÃuo;sllah.Mqªme qu’on apprend moins maintenant aux enfants les rites, ce qui a pour conséquences de ne pas savoir le faire, mais aussi de ne pas savoir le reconnaître.

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