[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 97

 
Mathemat >>:

2 Candid: циркуля нету, сын рисует прямо сейчас. Да и концентрироваться на приближенном решении, наверно, не стоит - хотя оно может быть вполне элегантным.

It is simply hoped that when they are precisely constructed they will suddenly lie on a line or a circle, then there will be extra stimulus to think about where that line or circle arises from.

 

Let's give it a try. I'll try to rent a circular from my son. Although you can probably do it without him.

 
Mathemat >>:

В квадрате отметили по точке на каждой стороне, а сам квадрат стёрли. Восстановите его.

Mark points A, B, C, D on the circle.

draw a line parallel to AC through point B,

from this line create a perpendicular line going through point B,

from point B on that perpendicular line, take a line segment equal to AC, on the D side, we will have point E.

The line DE will be one of the sides of the square.

then it is simple, parallel-perpendicular :)


R.S.: quadrilateral ABCD doesn't have to be a square.

 

Exactly, Swan! It was enough to construct another "diagonal" equal to the AC and perpendicular to it.

 
Mathemat >>:

Давай попробуем. Я буду пытаться арендовать циркуль у сына. Хотя, наверно, и без него можно.

So, Swan has cancelled it looks like. We'll have to think about his decision some more.


P.S. Yes, that's it, I agree.

 

Obviously, the construction does not work when the diagonals are perpendicular (the quadrilateral is not a square) - the same AC and BE. Maybe here too the square is any arbitrary rectangle circumscribed around this quadrilateral? Let's check on our equation...

 
So, whether as a scarecrow or as a carcass, you have to get out of the branch :)
 
Mathemat >>:

Очевидно, построение не работает, когда диагонали перпендикулярны (четырехугольник - не квадрат) - те же АС и ВЕ.

Yes, parallel is unnecessary, a perpendicular to AC is possible.

What to do if AC is perpendicular to BD remains to be solved.

 
Candid >>:
Так, хоть виде чучела, хоть в виде тушки, но из ветки надо сваливать :)


there, there :-)))
 
Candid >>:
Так, Swan отменил похоже. Надо ещё пообдумывать его решение.

Seems about right. Nice. Really compact and witty.

Reason: