17
votes
4answers
4k views

Two paradoxes: $\pi = 2$ and $\sqrt 2 = 2$ [duplicate]

Possible Duplicate: Is value of $\pi = 4$? Can anyone explain how to properly resolve two paradoxes in this YouTube video by James Tanton?
7
votes
2answers
999 views

Problem with the Pythagorean theorem [duplicate]

The Pythagorean theorem has already been proved and it is a basic fact of math. It always works, and there are proofs of it. But I have found a problem. Say you want to get from point ...
1
vote
1answer
228 views

Is $\pi = 4$ really? [duplicate]

Can anyone explain what's wrong with this?
0
votes
2answers
155 views

Constructing a circle from a square [duplicate]

I have seen a [picture like this] several times: featuring a "troll proof" that $\pi=4$. Obviously the construction does not yield a circle, starting from a square, but how to rigorously and ...
-1
votes
1answer
212 views

How to find the area. Linked with another question. [duplicate]

Possible Duplicate: Is value of $\pi = 4$? In this question we discussed why the fake proof is wrong. But, what about the area? The process converges to the same area of the circle ...
1
vote
1answer
103 views

How does $a² + b² = c²$ work with 'steps'? [duplicate]

We all know that $a²+b²=c²$ in a right-angled triangle, and therefore, that $c<a+b$, so that walking along the red line would be shorter than using the two black lines to get from top left to ...
1
vote
0answers
128 views

contradicting PI=4 fallacy. [duplicate]

Possible Duplicate: Is value of $\pi = 4$? I know that you can take area out of a square without changing it's perimeter. Now, here's this problem: Draw a circle with dia = 1; Draw a ...
3
votes
0answers
69 views

Pythagorean “Paradox” (right-angled triangle). [duplicate]

Consider an isosceles right-angled triangle as shown in the figure (top left). The length of its hypotenuse is $c$. The figure distinguishes both legs of the triangle, however, from now on let's ...
1
vote
1answer
57 views

Length of diagonal compared to the limit of lengths of stair-shaped curves converging to it [duplicate]

I see this post and I am stunned. I think this is fallacious but I can't figure where is the fallacy? If you know the fallacy. Please post a answer.
-2
votes
1answer
38 views

What is wrong with this reasoning when calculating circle perimeter? [duplicate]

Looking at the following image, which was posted on the internet: Could someone tell me what is wrong? It seems true for the first 4 small images. But, when it comes to infinitesimal length, ...
2
votes
0answers
32 views

Math for Little Kids: Pseudo-Proof [duplicate]

A popular maths comic strip for little kid is shown in below: Why, this proof is wrong? And, what happen when you comparing the areas of these two figure (truncate square, and circle)? Are the area ...
4
votes
0answers
20 views

How come the diagonal of a right triangle is not the same as the total distance of the adjacent and opposite leg? [duplicate]

Disclaimer: This might seem like a very dumb question. But I rather ask it and learn than to never ask at all and always wonder. Also, to me it is confusing, you guys are probably much more advance in ...
110
votes
44answers
13k views

What's your favorite proof accessible to a general audience? [closed]

What math statement with proof do you find most beautiful and elegant, where such is accessible to a general audience, meaning you could state, prove, and explain it to a general audience in ...
149
votes
27answers
26k views

Best Fake Proofs? (A M.SE April Fools Day collection) [closed]

In honor of April Fools Day 2013, I'd like this question to collect the best, most convincing fake proofs of impossibilities you have seen. I've posted one as an answer below. I'm also thinking of a ...
94
votes
20answers
19k views

Visually deceptive “proofs” which are mathematically wrong [closed]

Related: Visually stunning math concepts which are easy to explain Beside the wonderful examples above, there should also be counterexamples, where visually intuitive demonstrations are actually ...

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