Christian Blatter

ETH Zurich (Switzerland)

math.ethz.ch/~blatter

Age: 79

1h
answered Total no. of Transitive Relation on $A = \{a,b,c\}$
19h
answered $a^2 = 2b^3 = 3c^5$ Find the smallest value of $abc$.
19h
answered Where could (do?) we go after exhausting greek letters?
1d
answered What is the geometrical difference between continuity and uniform continuity?
1d
revised Expected area of triangle formed by three random points inside unit circle
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2d
comment A fun problem by Arnold using the Poincaré recurrence theorem
@justhalf: To the contrary: SBareS answer is a confirmation of mine and gives additional details.
2d
comment Expected area of triangle formed by three random points inside unit circle
@Jack D'Aurizio: I guess in the handling of the conditional expectations.
2d
answered A fun problem by Arnold using the Poincaré recurrence theorem
2d
comment Expected area of triangle formed by three random points inside unit circle
I think this is wrong by a margin of $0.02$; see my answer below.
2d
answered Expected area of triangle formed by three random points inside unit circle
2d
awarded Good Answer
Apr
20
comment A trigonometric proof of an inequality
Above all, it comes from the chain rule!
Apr
20
comment How do I compute the density of R?
@Hernant Rupani: I had overseen that the OP had already used $X$ for the cut point. I therefore have replaced my $X$ by $S$, which has density $2$, as stated. Hope it's clear now.
Apr
20
revised How do I compute the density of R?
edited body
Apr
20
revised Is it possible to solve the Zebra Puzzle/Einstein's Riddle using pure math?
edited body
Apr
20
answered A trigonometric proof of an inequality
Apr
20
answered $f(x)$ is Riemann integrable $\Rightarrow$ $\frac{1}{1 + f^2(x)}$ is Riemann integrable
Apr
20
revised Power set equinumerosity. Is this proof correct?
added 331 characters in body
Apr
19
answered Geometry with complex numbers.
Apr
19
comment Geometry with complex numbers.
I think that your end result is correct, but I don't see why these angles should add up to $180^\circ$. It's the opposite angles in a circular quadrilateral that add up to $180^\circ$.
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