[/quote]
,
,
,
be positive real numbers such that 
.![$$\sqrt[3]{(a^2+1)(b^2+1)(c^2+1)} \le \left(\frac{a+b+c}{3}\right)^2 + 1.$$](http://latex.artofproblemsolving.com/2/0/7/207934bca53047858a3820f37705171ff0abfd45.png)
and 
and 
Prove that![\[\frac{a}{(b+c-a)^2} + \frac{b}{(c+a-b)^2} + \frac{c}{(a+b-c)^2} \geq \frac{3}{(abc)^2}.\]](http://latex.artofproblemsolving.com/0/a/b/0ab4b4e6c28a1ae67788525642661dbcd04d0bd8.png)
such that ![\[ f(x^2 + yf(z)) = xf(x) + zf(y) , \]](http://latex.artofproblemsolving.com/2/b/a/2baee1d8464992fc38a16561b48b18f4b35807bd.png)
for all 
.
steps and has to reach 
is valid but 
is not valid.
,
lie on a line in this order and satisfy 
.
be the midpoints of 
and 
,
is acute, and let 
be its orthocentre. Points 
and 
lie on lines 
and 
,
and 
and 
and 
such for any 
.
satisfy,
Where 
}
be an integer. We are given a balance and 
weights of weight 
.
to satisfy that the equation 
has at least 1 roots 
of positive integers is called central if for every positive integer 
terms of the sequence is equal to 
,
,
,
of positive integers such that for every central sequence 
,
,
,
.
of the equation![\[n^3=p^2-p-1\]](http://latex.artofproblemsolving.com/f/f/8/ff88093bb0aa93afcfdff3ae25149ec5fbacb61f.png)
is a prime number and 
?
be an integer. In a configuration of an 
board, each of the 
cells contains an arrow, either pointing up, down, left, or right. Given a starting configuration, Turbo the snail starts in one of the cells of the board and travels from cell to cell. In each move, Turbo moves one square unit in the direction indicated by the arrow in her cell (possibly leaving the board). After each move, the arrows in all of the cells rotate 
counterclockwise. We call a cell good if, starting from that cell, Turbo visits each cell of the board exactly once, without leaving the board, and returns to her initial cell at the end. Determine, in terms of 
Y by
In an acute-angled triangle 
, the bisector of the angle 
intersects the circle circumscribed around this triangle at the point 
. From the point on the line 
the perpendicular 
was drawn, and from the center of the inscribed circle 
of the same triangle the perpendicular 
was drawn on the line . Let 
be the midpoint of the segment 
. Prove that the line 
passes through the midpoint of the segment 
.
(Mykola Moroz)
, the bisector of the angle 
intersects the circle circumscribed around this triangle at the point 
. From the point on the line 
the perpendicular 
was drawn, and from the center of the inscribed circle 
of the same triangle the perpendicular 
was drawn on the line . Let 
be the midpoint of the segment 
. Prove that the line 
passes through the midpoint of the segment 
.(Mykola Moroz)
This post has been edited 1 time. Last edited by parmenides51, Jun 21, 2022, 2:35 AM
.
is the intersection of 
is cyclic.
Then we get the desired cyclic quadrilateral.
.
is perpendicular to 
and 
.
