V \le RS/2 in tetrahderon with equil base
by Miquel-point, Apr 6, 2025, 7:54 PM
Consider a tetrahedron
with
equilateral. Let
be the area of the triangle of sides
,
and
. Show that
where
is the circumradius and
is the volume of the tetrahedron.
Stere Ianuș









Stere Ianuș
Arithmetic properties of ax^2-x/6
by Miquel-point, Apr 6, 2025, 7:50 PM
Let
where
.
1) Determine
such that for every
we have
.
2) Show that if
is irrational then for every
there exists
such that
Generalize the problem!


1) Determine



2) Show that if



![\[u<P(n)-\lfloor P(n)\rfloor <v.\]](http://latex.artofproblemsolving.com/9/4/a/94a8cb1f064e1dea37e8894fb4fd4e34c4c6c845.png)
Point moving towards vertices and changing plans again and again
by Miquel-point, Apr 6, 2025, 7:47 PM
In the plane of traingle
we consider a variable point
which moves on line
towards
. Halfway there, it stops and starts moving in a straight line line towards
. Halfway there, it stops and starts moving in a straight line towards
, and halfway there it stops and starts moving in a straight line towards
, and so on. Show that
will get as close as we want to the vertices of a fixed triangle with area
.









max(PA,PC) when ABCD square
by Miquel-point, Apr 6, 2025, 6:15 PM
Determine the set of points
in the plane of a square
for which ![\[\max (PA, PC)=\frac1{\sqrt2}(PB+PD).\]](//latex.artofproblemsolving.com/3/9/8/3984b1970837a85af0bac93fd711843630a1fd99.png)
Titu Andreescu and I.V. Maftei


![\[\max (PA, PC)=\frac1{\sqrt2}(PB+PD).\]](http://latex.artofproblemsolving.com/3/9/8/3984b1970837a85af0bac93fd711843630a1fd99.png)
Titu Andreescu and I.V. Maftei
This post has been edited 1 time. Last edited by Miquel-point, 2 hours ago
functional equation
by hanzo.ei, Apr 6, 2025, 6:08 PM
Two Functional Inequalities
by Mathdreams, Apr 6, 2025, 1:34 PM
Determine all functions
such that
and
for any real numbers
and
.
(Miroslav Marinov, Bulgaria)





(Miroslav Marinov, Bulgaria)
Beautiful problem
by luutrongphuc, Apr 4, 2025, 5:35 AM
Let triangle
be circumscribed about circle
, and let
be the orthocenter of
. The circle
touches line
at
. The tangent to the circle
at
meets
at
. Let
be the midpoint of
, and let the line
meet
again at
. The tangent to
parallel to
meets the line
at
. Prove that
is tangent to
.






















Incircle-excircle config geo
by a_507_bc, Apr 4, 2024, 4:26 PM
Let
be a triangle with incenter and
-excenter
, whose incircle touches
at
. The line
meets
at
and
is the midpoint of
. Show that
.











Every subset of size k has sum at most N/2
by orl, Apr 20, 2006, 5:58 PM
For a given positive integer
find, in terms of
, the minimum value of
for which there is a set of
distinct positive integers that has sum greater than
but every subset of size
has sum at most 







Stay insane,Coz it's your will, labour and pain,which takes you to the top of the mountain.
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