Summing the GCD of a number and the divisors of another.
by EmersonSoriano, Apr 2, 2025, 10:03 PM
For each pair of positive integers
and
, we define
as follows:
where
are all the positive divisors of
. For example,
.
Find all positive integers
such that
.
Find all positive integers
such that
.













Locus of a point on the side of a square
by EmersonSoriano, Apr 2, 2025, 9:58 PM
Let
be a fixed square and
a variable point on segment
. The square
is constructed such that
is on segment
and
is on segment
. Let
be the intersection point of lines
and
. Find the locus of
as
varies along segment
.














Chess queens on a cylindrical board
by EmersonSoriano, Apr 2, 2025, 9:56 PM
Let
be a positive integer. In an
board, two opposite sides have been joined, forming a cylinder. Determine whether it is possible to place
queens on the board such that no two threaten each other when:
.
.







Classic complex number geo
by Ciobi_, Apr 2, 2025, 12:56 PM
Let
be a point in the plane, distinct from the vertices of
. Consider
the reflections of
with respect to lines
and
, in this order.
a) Prove that
are collinear if and only if
lies on the circumcircle of
.
b) If
does not lie on the circumcircle of
and the centroids of triangles
and
coincide, prove that
is equilateral.






a) Prove that



b) If





Olympiad Geometry problem-second time posting
by kjhgyuio, Apr 2, 2025, 1:03 AM
In trapezium ABCD,AD is parallel to BC and points E and F are midpoints of AB and DC respectively. If
Area of AEFD/Area of EBCF =√3 + 1/3-√3 and the area of triangle ABD is √3 .find the area of trapezium ABCD
Area of AEFD/Area of EBCF =√3 + 1/3-√3 and the area of triangle ABD is √3 .find the area of trapezium ABCD
kind of well known?
by dotscom26, Apr 1, 2025, 4:11 AM
Let
be real numbers satisfying

Find the maximum value of

I have seen many problems with the same structure, Id really appreciate if someone could explain which approach is suitable here


Find the maximum value of

I have seen many problems with the same structure, Id really appreciate if someone could explain which approach is suitable here
This post has been edited 1 time. Last edited by dotscom26, Tuesday at 4:20 AM
Thanks u!
by Ruji2018252, Mar 26, 2025, 8:45 AM
Find all
and
![\[ f(x+y)+f(x^2+f(y))=f(f(x))^2+f(x)+f(y)+y,\forall x,y\in\mathbb{R}\]](//latex.artofproblemsolving.com/c/8/9/c895ae7fdf8d7f284ac9fc94cc077d6edad6cbf0.png)

![\[ f(x+y)+f(x^2+f(y))=f(f(x))^2+f(x)+f(y)+y,\forall x,y\in\mathbb{R}\]](http://latex.artofproblemsolving.com/c/8/9/c895ae7fdf8d7f284ac9fc94cc077d6edad6cbf0.png)
This post has been edited 1 time. Last edited by Ruji2018252, Mar 26, 2025, 9:30 AM
Reason: Sori
Reason: Sori
Famous geo configuration appears on the district MO
by AndreiVila, Mar 8, 2025, 1:28 PM
Let
be a convex hexagon with
and
.



- Prove that there is a unique point
which is equidistant from sides
and
.
- If
and
are the centers of mass of
and
, show that
.
Sum of whose elements is divisible by p
by nntrkien, Aug 8, 2004, 1:29 AM
Let
be an odd prime number. How many
-element subsets
of
are there, the sum of whose elements is divisible by
?





"Where wisdom and valor fail, all that remains is faith. . . And it can overcome all." -Toa Mata Tahu
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