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Halykov   0
5 minutes ago
Source: own
Let \( ABC \) be a scalene triangle with circumcircle \( \Gamma \) and circumcircle \( O \). Denote \( M \) and \( N \) as the midpoints of \( AC \) and \( BC \), respectively. The altitude from \( A \) to \( BC \) intersects \( \Gamma \) again at \( D \). The line \( DN \) meets \( \Gamma \) a second time at \( T \), and \( AT \) intersects \( BC \) at \( X \). The perpendicular bisector of \( AC \) intersects \( AD \) at \( S \) and \( AB \) at \( Z \). Let the circumcircle of \( \triangle XMZ \) intersect \( BC \) again at \( Y \), and let the line \( ZY \) intersect \( AD \) at \( K \).
If \( H \) is the reflection of \( S \) over \( K \), prove that the intersection of \( CH \) and \( BM \) lies on the circumcircle of \( BOC \).
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Halykov
5 minutes ago
0 replies
Olympiad Problems Correlation with Computational?
FuturePanda   8
N Today at 3:46 AM by deduck
Hi everyone,

Recently I;ve started doing a lot of nice combo/algebra Olympiad problems(JMO, PAGMO, CMO, etc.) and I’ve got to say, it’s been pretty fun(I’m enjoying it!). I was wondering if doing Olympiad problems also helps increase computational abilities slightly. Currently I am doing 75% computational, 25% oly but if anyone has any expreience I want to switch it to 25% computational and 75% Olympiad, though I still want to have computational skills for ARML, AIME, SMT, BMT, HMMT, etc.

If anyone has any experience, please let me know!

Thank you so much in advance!
8 replies
FuturePanda
Apr 26, 2025
deduck
Today at 3:46 AM
9 Mathpath vs. AMSP
FuturePanda   32
N Today at 12:11 AM by gavinhaominwang
Hi everyone,

For an AIME score of 7-11, would you recommend MathPath or AMSP Level 2/3?

Thanks in advance!
Also people who have gone to them, please tell me more about the programs!
32 replies
FuturePanda
Jan 30, 2025
gavinhaominwang
Today at 12:11 AM
sussy baka stop intersecting in my lattice points
Spectator   24
N Yesterday at 11:56 PM by ilikemath247365
Source: 2022 AMC 10A #25
Let $R$, $S$, and $T$ be squares that have vertices at lattice points (i.e., points whose coordinates are both integers) in the coordinate plane, together with their interiors. The bottom edge of each square is on the x-axis. The left edge of $R$ and the right edge of $S$ are on the $y$-axis, and $R$ contains $\frac{9}{4}$ as many lattice points as does $S$. The top two vertices of $T$ are in $R \cup S$, and $T$ contains $\frac{1}{4}$ of the lattice points contained in $R \cup S$. See the figure (not drawn to scale).

IMAGE

The fraction of lattice points in $S$ that are in $S \cap T$ is 27 times the fraction of lattice points in $R$ that are in $R \cap T$. What is the minimum possible value of the edge length of $R$ plus the edge length of $S$ plus the edge length of $T$?

$\textbf{(A) }336\qquad\textbf{(B) }337\qquad\textbf{(C) }338\qquad\textbf{(D) }339\qquad\textbf{(E) }340$
24 replies
Spectator
Nov 11, 2022
ilikemath247365
Yesterday at 11:56 PM
JSMC texas
BossLu99   27
N Yesterday at 11:53 PM by miles888
who is going to JSMC texas
27 replies
BossLu99
Apr 28, 2025
miles888
Yesterday at 11:53 PM
Question
HopefullyMcNats2025   19
N Yesterday at 10:29 PM by MC_ADe
Is it more difficult to make MOP or make usajmo, usapho, and usabo
19 replies
HopefullyMcNats2025
Apr 7, 2025
MC_ADe
Yesterday at 10:29 PM
System
worthawholebean   10
N Yesterday at 9:24 PM by daijobu
Source: AIME 2008II Problem 14
Let $ a$ and $ b$ be positive real numbers with $ a\ge b$. Let $ \rho$ be the maximum possible value of $ \frac{a}{b}$ for which the system of equations
\[ a^2+y^2=b^2+x^2=(a-x)^2+(b-y)^2\]has a solution in $ (x,y)$ satisfying $ 0\le x<a$ and $ 0\le y<b$. Then $ \rho^2$ can be expressed as a fraction $ \frac{m}{n}$, where $ m$ and $ n$ are relatively prime positive integers. Find $ m+n$.
10 replies
worthawholebean
Apr 3, 2008
daijobu
Yesterday at 9:24 PM
Mathcounts state
happymoose666   33
N Yesterday at 9:19 PM by tikachaudhuri
Hi everyone,
I just have a question. I live in PA and I sadly didn't make it to nationals this year. Is PA a competitive state? I'm new into mathcounts and not sure
33 replies
happymoose666
Mar 24, 2025
tikachaudhuri
Yesterday at 9:19 PM
2025 ELMOCOUNTS - Mock MATHCOUNTS Nationals
vincentwant   135
N Yesterday at 2:11 PM by Soupboy0
text totally not copied over from wmc (thanks jason <3)
Quick Links:
[list=disc]
[*] National: (Sprint) (Target) (Team) (Sprint + Target Submission) (Team Submission) [/*]
[*] Miscellaneous: (Leaderboard) (Sprint + Target Private Discussion Forum) (Team Discussion Forum)[/*]
[/list]
-----
Eddison Chen (KS '22 '24), Aarush Goradia (CO '24), Ethan Imanuel (NJ '24), Benjamin Jiang (FL '23 '24), Rayoon Kim (PA '23 '24), Jason Lee (NC '23 '24), Puranjay Madupu (AZ '23 '24), Andy Mo (OH '23 '24), George Paret (FL '24), Arjun Raman (IN '24), Vincent Wang (TX '24), Channing Yang (TX '23 '24), and Jefferson Zhou (MN '23 '24) present:



[center]IMAGE[/center]

[center]Image credits to Simon Joeng.[/center]

2024 MATHCOUNTS Nationals alumni from all across the nation have come together to administer the first-ever ELMOCOUNTS Competition, a mock written by the 2024 Nationals alumni given to the 2025 Nationals participants. By providing the next generation of mathletes with free, high quality practice, we're here to boast how strong of an alumni community MATHCOUNTS has, as well as foster interest in the beautiful art that is problem writing!

The tests and their corresponding submissions forms will be released here, on this thread, on Monday, April 21, 2025. The deadline is May 10, 2025. Tests can be administered asynchronously at your home or school, and your answers should be submitted to the corresponding submission form. If you include your AoPS username in your submission, you will be granted access to the private discussion forum on AoPS, where you can discuss the tests even before the deadline.
[list=disc]
[*] "How do I know these tests are worth my time?" [/*]
[*] "Who can participate?" [/*]
[*] "How do I sign up?" [/*]
[*] "What if I have multiple students?" [/*]
[*] "What if a problem is ambiguous, incorrect, etc.?" [/*]
[*] "Will there be solutions?" [/*]
[*] "Will there be a Countdown Round administered?" [/*]
[/list]
If you have any other questions, feel free to email us at elmocounts2025@gmail.com (or PM me)!
135 replies
vincentwant
Apr 20, 2025
Soupboy0
Yesterday at 2:11 PM
Jumping on Lily Pads to Avoid a Snake
brandbest1   53
N Yesterday at 5:14 AM by ESAOPS
Source: 2014 AMC 10B #25 & 2014 AMC 12B #22
In a small pond there are eleven lily pads in a row labeled $0$ through $10$. A frog is sitting on pad $1$. When the frog is on pad $N$, $0<N<10$, it will jump to pad $N-1$ with probability $\frac{N}{10}$ and to pad $N+1$ with probability $1-\frac{N}{10}$. Each jump is independent of the previous jumps. If the frog reaches pad $0$ it will be eaten by a patiently waiting snake. If the frog reaches pad $10$ it will exit the pond, never to return. What is the probability that the frog will escape being eaten by the snake?

$ \textbf {(A) } \frac{32}{79} \qquad \textbf {(B) } \frac{161}{384} \qquad \textbf {(C) } \frac{63}{146} \qquad \textbf {(D) } \frac{7}{16} \qquad \textbf {(E) } \frac{1}{2} $
53 replies
brandbest1
Feb 20, 2014
ESAOPS
Yesterday at 5:14 AM
How many people get waitlisted st promys?
dragoon   28
N Yesterday at 2:12 AM by ThriftyPiano
Asking for a friend here
28 replies
dragoon
Apr 18, 2025
ThriftyPiano
Yesterday at 2:12 AM
Mock 22nd Thailand TMO P9
korncrazy   1
N Apr 14, 2025 by ItzsleepyXD
Source: own
Let $H_A,H_B,H_C$ be the feet of the altitudes of the triangle $ABC$ from $A,B,C$, respectively. $P$ is the point on the circumcircle of the triangle $ABC$, $H$ is the orthocenter of the triangle $ABC$, and the incircle of triangle $H_AH_BH_C$ has radius $r$. Let $T_A$ be the point such that $T_A$ and $H$ are on the opposite side of $H_BH_C$, line $T_AP$ is perpendicular to the line $H_BH_C$, and the distance from $T_A$ to line $H_BH_C$ is $r$. Define $T_B$ and $T_C$ similarly. Prove that $T_A,T_B,T_C$ are collinear.
1 reply
korncrazy
Apr 13, 2025
ItzsleepyXD
Apr 14, 2025
Mock 22nd Thailand TMO P9
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Source: own
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korncrazy
41 posts
#1
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Let $H_A,H_B,H_C$ be the feet of the altitudes of the triangle $ABC$ from $A,B,C$, respectively. $P$ is the point on the circumcircle of the triangle $ABC$, $H$ is the orthocenter of the triangle $ABC$, and the incircle of triangle $H_AH_BH_C$ has radius $r$. Let $T_A$ be the point such that $T_A$ and $H$ are on the opposite side of $H_BH_C$, line $T_AP$ is perpendicular to the line $H_BH_C$, and the distance from $T_A$ to line $H_BH_C$ is $r$. Define $T_B$ and $T_C$ similarly. Prove that $T_A,T_B,T_C$ are collinear.
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ItzsleepyXD
127 posts
#2
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$P' =$ midpoint of $HP$.
note that $P'$ are on nine-point circle of $\triangle ABC$ and $H$ is incenter of $\triangle H_AH_BH_C$ .
Let $X,Y,Z$ be midpoint of $HT_A,HT_B,HT_C$ . so it sufficient to prove that $X,Y,Z$ collinear .
Let $D,E,F$ be point that incircle of $\triangle H_AH_BH_C$ touch side $H_BH_C,H_CH_A,H_AH_B$ respectively.
Let $P_A,P_B,P_C$ be projection $P$ to line $H_BH_C,H_CH_A,H_AH_B$ respectively.
it is easy to see that $X,Y,Z$ are midpoint of $DP_A,EP_B,FP_C$ respectively.
By simson line of point $P'$ wrt $\triangle H_AH_BH_C$ it is known that $X,Y,Z$ is collinear . done $\square$
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