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Re: beautiful math demonstrations
Posted: Thu Nov 03, 2011 11:53 pm
by cyclops
Bill Spight wrote:
You mean two flips to make a rotation, right?
My proof is so beautiful; it deserves better explanation.
So let M, the center of the circle, lie on AB. A, B and C on the circle.
Get your scissors and cut out triangle ABC. Fold MA on MC and MB on MC. Rub it flat. You are left with a rectangle.
Re: beautiful math demonstrations
Posted: Fri Nov 04, 2011 2:59 am
by flOvermind
I honestly don't see why you should get a rectangle (that is, without the prior knowledge that the angle is 90 degrees
)...
Re: beautiful math demonstrations
Posted: Fri Nov 04, 2011 3:52 am
by bayu
flOvermind wrote:I honestly don't see why you should get a rectangle (that is, without the prior knowledge that the angle is 90 degrees
)...
Proof by staring
The other three angles are automatically 90 degrees
hence, so is the fourth one.
Great proof!
Re: beautiful math demonstrations
Posted: Fri Nov 04, 2011 5:11 am
by flOvermind
Ah, I missed that. Nice proof indeed
Re: beautiful math demonstrations
Posted: Fri Nov 04, 2011 7:03 am
by cyclops
As usual I was too terse. Now for some other nice proofs.
The proof that no rational squares to 2; that e doesn't solve a rational polynomial equation.
And the impossibilities: By construction: trisect an angle, double a cube, measure pi.
The non existence of a formula solving a general polynomial equation of degree higher than 4.