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k a May Highlights and 2025 AoPS Online Class Information
jlacosta   0
May 1, 2025
May is an exciting month! National MATHCOUNTS is the second week of May in Washington D.C. and our Founder, Richard Rusczyk will be presenting a seminar, Preparing Strong Math Students for College and Careers, on May 11th.

Are you interested in working towards MATHCOUNTS and don’t know where to start? We have you covered! If you have taken Prealgebra, then you are ready for MATHCOUNTS/AMC 8 Basics. Already aiming for State or National MATHCOUNTS and harder AMC 8 problems? Then our MATHCOUNTS/AMC 8 Advanced course is for you.

Summer camps are starting next month at the Virtual Campus in math and language arts that are 2 - to 4 - weeks in duration. Spaces are still available - don’t miss your chance to have an enriching summer experience. There are middle and high school competition math camps as well as Math Beasts camps that review key topics coupled with fun explorations covering areas such as graph theory (Math Beasts Camp 6), cryptography (Math Beasts Camp 7-8), and topology (Math Beasts Camp 8-9)!

Be sure to mark your calendars for the following upcoming events:
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[*]May 20th, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 1 Math Jam, Problems 1 to 4, join the Canada/USA Mathcamp staff for this exciting Math Jam, where they discuss solutions to Problems 1 to 4 of the 2025 Mathcamp Qualifying Quiz!
[*]May 21st, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 2 Math Jam, Problems 5 and 6, Canada/USA Mathcamp staff will discuss solutions to Problems 5 and 6 of the 2025 Mathcamp Qualifying Quiz![/list]
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0 replies
jlacosta
May 1, 2025
0 replies
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k i Adding contests to the Contest Collections
dcouchman   1
N Apr 5, 2023 by v_Enhance
Want to help AoPS remain a valuable Olympiad resource? Help us add contests to AoPS's Contest Collections.

Find instructions and a list of contests to add here: https://artofproblemsolving.com/community/c40244h1064480_contests_to_add
1 reply
dcouchman
Sep 9, 2019
v_Enhance
Apr 5, 2023
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k i Zero tolerance
ZetaX   49
N May 4, 2019 by NoDealsHere
Source: Use your common sense! (enough is enough)
Some users don't want to learn, some other simply ignore advises.
But please follow the following guideline:


To make it short: ALWAYS USE YOUR COMMON SENSE IF POSTING!
If you don't have common sense, don't post.


More specifically:

For new threads:


a) Good, meaningful title:
The title has to say what the problem is about in best way possible.
If that title occured already, it's definitely bad. And contest names aren't good either.
That's in fact a requirement for being able to search old problems.

Examples:
Bad titles:
- "Hard"/"Medium"/"Easy" (if you find it so cool how hard/easy it is, tell it in the post and use a title that tells us the problem)
- "Number Theory" (hey guy, guess why this forum's named that way¿ and is it the only such problem on earth¿)
- "Fibonacci" (there are millions of Fibonacci problems out there, all posted and named the same...)
- "Chinese TST 2003" (does this say anything about the problem¿)
Good titles:
- "On divisors of a³+2b³+4c³-6abc"
- "Number of solutions to x²+y²=6z²"
- "Fibonacci numbers are never squares"


b) Use search function:
Before posting a "new" problem spend at least two, better five, minutes to look if this problem was posted before. If it was, don't repost it. If you have anything important to say on topic, post it in one of the older threads.
If the thread is locked cause of this, use search function.

Update (by Amir Hossein). The best way to search for two keywords in AoPS is to input
[code]+"first keyword" +"second keyword"[/code]
so that any post containing both strings "first word" and "second form".


c) Good problem statement:
Some recent really bad post was:
[quote]$lim_{n\to 1}^{+\infty}\frac{1}{n}-lnn$[/quote]
It contains no question and no answer.
If you do this, too, you are on the best way to get your thread deleted. Write everything clearly, define where your variables come from (and define the "natural" numbers if used). Additionally read your post at least twice before submitting. After you sent it, read it again and use the Edit-Button if necessary to correct errors.


For answers to already existing threads:


d) Of any interest and with content:
Don't post things that are more trivial than completely obvious. For example, if the question is to solve $x^{3}+y^{3}=z^{3}$, do not answer with "$x=y=z=0$ is a solution" only. Either you post any kind of proof or at least something unexpected (like "$x=1337, y=481, z=42$ is the smallest solution). Someone that does not see that $x=y=z=0$ is a solution of the above without your post is completely wrong here, this is an IMO-level forum.
Similar, posting "I have solved this problem" but not posting anything else is not welcome; it even looks that you just want to show off what a genius you are.

e) Well written and checked answers:
Like c) for new threads, check your solutions at least twice for mistakes. And after sending, read it again and use the Edit-Button if necessary to correct errors.



To repeat it: ALWAYS USE YOUR COMMON SENSE IF POSTING!


Everything definitely out of range of common sense will be locked or deleted (exept for new users having less than about 42 posts, they are newbies and need/get some time to learn).

The above rules will be applied from next monday (5. march of 2007).
Feel free to discuss on this here.
49 replies
ZetaX
Feb 27, 2007
NoDealsHere
May 4, 2019
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Mathcounts Nationals Written Score Hub
DhruvJha   2
N 10 minutes ago by iwastedmyusername
Put in your estimated score on the written nats comp on Sunday after the comp so we can get a good idea of the cdr quals are
2 replies
DhruvJha
42 minutes ago
iwastedmyusername
10 minutes ago
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9 What is the best way to learn math???
lovematch13   99
N 14 minutes ago by GallopingUnicorn45
On the contrary, I'm also gonna try to send this to school admins. PLEASE DO NOT TROLL!!!!
99 replies
lovematch13
May 22, 2023
GallopingUnicorn45
14 minutes ago
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A glass is filled with milk. Two-thirds of its content is poured out and replace
Vulch   5
N 22 minutes ago by valisaxieamc
A glass is filled with milk. Two-thirds of its content is poured out and replaced with water. If this process of pouring out two-thirds the content and replacing with water is repeated three more times, then the final ratio of milk to water in the glass, is
5 replies
Vulch
Today at 8:53 AM
valisaxieamc
22 minutes ago
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Many Equal Sides
mathisreal   3
N 23 minutes ago by QueenArwen
Source: Brazil EGMO TST 2023 #1
Let $ABC$ be a triangle with $BA=BC$ and $\angle ABC=90^{\circ}$. Let $D$ and $E$ be the midpoints of $CA$ and $BA$ respectively. The point $F$ is inside of $\triangle ABC$ such that $\triangle DEF$ is equilateral. Let $X=BF\cap AC$ and $Y=AF\cap DB$. Prove that $DX=YD$.
3 replies
mathisreal
Nov 10, 2022
QueenArwen
23 minutes ago
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9 MathandAI4Girls!!!
Inaaya   20
N an hour ago by Inaaya
How many problems did y'all solve this year?
I clowned and started the pset the week before :oops:
Though I think if i used the time wisely, I could have at least solved 11 of them
ended up with 9 :wallbash_red:
20 replies
Inaaya
May 7, 2025
Inaaya
an hour ago
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Calculus
youochange   1
N an hour ago by youochange
Find the area enclosed by the curves $e^x,e^{-x},x^2+y^2=1$
1 reply
youochange
2 hours ago
youochange
an hour ago
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Indian Geo
Adywastaken   0
an hour ago
Source: NMTC 2024/5
$\triangle ABC$ has $\angle A$ obtuse. Let $D$, $E$, $F$ be the feet of the altitudes from $A$, $B$, $C$ respectively. Let $A_1$, $B_1$, $C_1$ be arbitrary points on $BC$, $CA$, $AB$ respectively. The circles with diameter $AA_1$, $BB_1$, $CC_1$ are drawn. Show that the lengths of the tangents from the orthocentre of $ABC$ to these circles are equal.
0 replies
Adywastaken
an hour ago
0 replies
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Angle ratio
Adywastaken   0
an hour ago
Source: NMTC Junior 2024/4
An acute angle triangle $\triangle PQR$ is inscribed in a circle. Given $\angle P=\frac{\pi}{3}$ and $\angle R>\angle Q$. Let $H$ and $I$ be the orthocentre and incentre of $\triangle PQR$ respectively. Find the ratio of $\angle PHI$ to $\angle PRQ$.
0 replies
Adywastaken
an hour ago
0 replies
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concyclic , touchpoints of incircle related
parmenides51   2
N an hour ago by Blackbeam999
Source: All-Russian MO 1994 Regional (R4) 11.3
A circle with center $O$ is tangent to the sides $AB$, $BC$, $AC$ of a triangle $ABC$ at points $E,F,D$ respectively. The lines $AO$ and $CO$ meet $EF$ at points $N$ and $M$. Prove that the circumcircle of triangle $OMN$ and points $O$ and $D$ lie on a line.
2 replies
parmenides51
Aug 26, 2024
Blackbeam999
an hour ago
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Geometry Parallel Proof Problem
CatalanThinker   5
N 2 hours ago by Tkn
Source: No source found, just yet, please share if you find it though :)
Let M be the midpoint of the side BC of triangle ABC. The bisector of the exterior angle of point A intersects the side BC in D. Let the circumcircle of triangle ADM intersect the lines AB and AC in E and F respectively. If the midpoint of EF is N, prove that MN || AD.
I have done some constructions, but still did not quite get to the answer, see diagram attached below
5 replies
CatalanThinker
Yesterday at 3:33 AM
Tkn
2 hours ago
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find angle
TBazar   6
N 2 hours ago by sunken rock
Given $ABC$ triangle with $AC>BC$. We take $M$, $N$ point on AC, AB respectively such that $AM=BC$, $CM=BN$. $BM$, $AN$ lines intersect at point $K$. If $2\angle AKM=\angle ACB$, find $\angle ACB$
6 replies
TBazar
May 8, 2025
sunken rock
2 hours ago
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Iranian geometry configuration
Assassino9931   1
N 3 hours ago by sami1618
Source: Al-Khwarizmi Junior International Olympiad 2025 P7
Let $ABCD$ be a cyclic quadrilateral with circumcenter $O$, such that $CD$ is not a diameter of its circumcircle. The lines $AD$ and $BC$ intersect at point $P$, so that $A$ lies between $D$ and $P$, and $B$ lies between $C$ and $P$. Suppose triangle $PCD$ is acute and let $H$ be its orthocenter. The points $E$ and $F$ on the lines $BC$ and $AD$, respectively, are such that $BD \parallel HE$ and $AC\parallel HF$. The line through $E$, perpendicular to $BC$, intersects $AD$ at $L$, and the line through $F$, perpendicular to $AD$, intersects $BC$ at $K$. Prove that the points $K$, $L$, $O$ are collinear.

Amir Parsa Hosseini Nayeri, Iran
1 reply
Assassino9931
Today at 9:39 AM
sami1618
3 hours ago
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Hard geometry
Lukariman   0
4 hours ago
Given triangle ABC, a line d intersects the sides AB, AC and the line BC at D, E, F respectively.

(a) Prove that the circles circumscribing triangles ADE, BDF and CEF pass through a point P and P belongs to the circumcircle of triangle ABC.

(b) Prove that the centers of the circles circumscribing triangles ADE, BDF, CEF and ABC are all on the circle.

(c) Let $O_a$,$ O_b$, $O_c$ be the centers of the circles circumscribing triangles ADE, BDF, CEF. Prove that the orthocenter of triangle $O_a$$O_b$$O_c$ belongs to d.

(d) Prove that the orthocenters of triangles ADE, ABC, BDF, CEF are collinear.
0 replies
Lukariman
4 hours ago
0 replies
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CGMO5: Carlos Shine's Fact 5
v_Enhance   61
N 4 hours ago by Adywastaken
Source: 2012 China Girl's Mathematical Olympiad
As shown in the figure below, the in-circle of $ABC$ is tangent to sides $AB$ and $AC$ at $D$ and $E$ respectively, and $O$ is the circumcenter of $BCI$. Prove that $\angle ODB = \angle OEC$.
IMAGE
61 replies
v_Enhance
Aug 13, 2012
Adywastaken
4 hours ago
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I cant find one problem
tanujkundu   9
N Apr 3, 2025 by vsarg
Does anybody know which problem is about when a number is a meteor and when a number is a shooting star?
9 replies
tanujkundu
Sep 17, 2024
vsarg
Apr 3, 2025
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I cant find one problem
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tanujkundu
8 posts
tanujkundu
#1 h  Sep 17, 2024, 3:00 AM
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Does anybody know which problem is about when a number is a meteor and when a number is a shooting star?
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aidan0626
1901 posts
aidan0626
#2 h  Sep 17, 2024, 3:37 AM • 1 Y
Y by vsarg
Hi, this description is very vague and we probably can't help you unless you have more information on what the problem is.
What website did you find it on?
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aaaaaaaabbbb
148 posts
aaaaaaaabbbb
#3 h  Sep 17, 2024, 8:11 AM • 1 Y
Y by vsarg
Can you give more clue? Which contest is it?

The only question I found about shooting is this one AIME
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kamuii
231 posts
kamuii
#4 h  Sep 17, 2024, 8:54 PM • 1 Y
Y by vsarg
I saw one about shooting stars in intro to counting and prob
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cyberhacker
402 posts
cyberhacker
#5 h  Sep 17, 2024, 11:26 PM
Y by
this one?
Attachments:
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aritkr
1 post
aritkr
#6 h  Dec 10, 2024, 11:36 PM • 1 Y
Y by vsarg
tanujkundu wrote:
Does anybody know which problem is about when a number is a meteor and when a number is a shooting star?

check the number theory book
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GallopingUnicorn45
378 posts
GallopingUnicorn45
#7 h  Dec 12, 2024, 4:44 PM • 1 Y
Y by vsarg
It's in the C&P Intro book, that's the only one I know of.
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tanujkundu
8 posts
tanujkundu
#8 h  Apr 2, 2025, 7:30 PM • 1 Y
Y by vsarg
Thank you, everyone! I appreciate your help.
This post has been edited 1 time. Last edited by tanujkundu, Apr 2, 2025, 7:30 PM
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sadas123
1270 posts
sadas123
#9 h  Apr 2, 2025, 8:35 PM • 1 Y
Y by vsarg
tanujkundu wrote:
Thank you, everyone! I appreciate your help.

There is a problem like that in NT.
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vsarg
277 posts
vsarg
#10 h  Apr 3, 2025, 1:47 AM
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I think thares a prowabiltyh quest leik thatt
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