(Warning: There is no solution video for this quesiton.)
(Warning: There is no solution video for this quesiton.) Now
-Do you know Lewis Carrol?      -I heard
 
 
Author of 'Alice in Wonderland'.
 
-Logician, Mathematician
At Cambridge
 
This is one of his favourite questions.
I take a rectangle like this
Then...
I spin this edge based on this point.
OK?
I will get one more colour...
 
green and orange
 
This pink,
equals to this
And this equals another one because it is turned, right?
Good, now
I draw a perpendecular line from middle point of the edge
I draw a perpendecular line from middle point of the edge
I draw a perpendecular line from middle point of the edge
and I combine those two points.
Take the mid point of this, too.
Take the mid point of this, too.
One more perpendicular line...
One more perpendicular line...
They cross each other
Naturally, due to perpendicular line,
This length...
Let me write this with blue one. Or green...
This length equals to, of course, this length
 
Because of the perpendicular line that is drawn from midpoint
Because of the perpendicular line that is drawn from midpoint
So those two lengths equals each other, right?  -Why?
Didn't I draw this exact middle point?
 
I have a line such like that
I have a line such like that
-I got it. -It's drawn from middle point
-It's drawn from midpoint,
-It's drawn from midpoint,
They are equal. This equals this, and this equals this.
This equals this, and this equals this.
This crosses midpoint of this thus...
Also crosses midpoint of this, right? -Yes
In this case,
Let do this with red.
Isn't this line equals to this line because of same reason? -Yes
Well
Pink, green, red... Pink, green, red...
 
They're equal
Two triangle, equal as edge-edge-edge
So triangles same
 
So this angle equals to...
this angle.
But this red one is a isosceles triangle.
-Yes
This angle equals this, isn't it?
I have a right angle when I subtract
and here a little more than a right angle.
 
Right angle gets equal to an angle which is not a right angle.
Does not exist any solution for this question?
So, you say, to leave our job? -[Laughter]
No, I didn't mean show the solution if there exists but I wonder so much whether...
it is abandoned or has a continuation solution?
Sure it has.
Of course there is a mistake somewhere.
(How can it be possible?)  -OK I got it
I leave finding the mistake to you
Everybody understood?
But you are not suprised. -I suprised but I do not reveal so much.
Actually, let me say...
 
There is no mistake.
 
Think about it. There should be a mistake somewhere, but...
actually there is not.
-Mistake is the case
(Good Luck) Mistake is somewhere else, think well, I won't say.
