ka March Highlights and 2025 AoPS Online Class Information
jlacosta0
Mar 2, 2025
March is the month for State MATHCOUNTS competitions! Kudos to everyone who participated in their local chapter competitions and best of luck to all going to State! Join us on March 11th for a Math Jam devoted to our favorite Chapter competition problems! Are you interested in training for MATHCOUNTS? Be sure to check out our AMC 8/MATHCOUNTS Basics and Advanced courses.
Are you ready to level up with Olympiad training? Registration is open with early bird pricing available for our WOOT programs: MathWOOT (Levels 1 and 2), CodeWOOT, PhysicsWOOT, and ChemWOOT. What is WOOT? WOOT stands for Worldwide Online Olympiad Training and is a 7-month high school math Olympiad preparation and testing program that brings together many of the best students from around the world to learn Olympiad problem solving skills. Classes begin in September!
Do you have plans this summer? There are so many options to fit your schedule and goals whether attending a summer camp or taking online classes, it can be a great break from the routine of the school year. Check out our summer courses at AoPS Online, or if you want a math or language arts class that doesn’t have homework, but is an enriching summer experience, our AoPS Virtual Campus summer camps may be just the ticket! We are expanding our locations for our AoPS Academies across the country with 15 locations so far and new campuses opening in Saratoga CA, Johns Creek GA, and the Upper West Side NY. Check out this page for summer camp information.
Be sure to mark your calendars for the following events:
[list][*]March 5th (Wednesday), 4:30pm PT/7:30pm ET, HCSSiM Math Jam 2025. Amber Verser, Assistant Director of the Hampshire College Summer Studies in Mathematics, will host an information session about HCSSiM, a summer program for high school students.
[*]March 6th (Thursday), 4:00pm PT/7:00pm ET, Free Webinar on Math Competitions from elementary through high school. Join us for an enlightening session that demystifies the world of math competitions and helps you make informed decisions about your contest journey.
[*]March 11th (Tuesday), 4:30pm PT/7:30pm ET, 2025 MATHCOUNTS Chapter Discussion MATH JAM. AoPS instructors will discuss some of their favorite problems from the MATHCOUNTS Chapter Competition. All are welcome!
[*]March 13th (Thursday), 4:00pm PT/7:00pm ET, Free Webinar about Summer Camps at the Virtual Campus. Transform your summer into an unforgettable learning adventure! From elementary through high school, we offer dynamic summer camps featuring topics in mathematics, language arts, and competition preparation - all designed to fit your schedule and ignite your passion for learning.[/list]
Our full course list for upcoming classes is below:
All classes run 7:30pm-8:45pm ET/4:30pm - 5:45pm PT unless otherwise noted.
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Introduction to Algebra A
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Intermediate: Grades 8-12
Intermediate Algebra
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Introduction to Programming with Python
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Given a fair -sided die with sides , consider the following game:
1. Roll the die. If the roll results in , you win immediately.
2. Otherwise, roll again. However, if the second roll is not greater than the previous roll, you lose.
3. Continue rolling until either:
- You roll , in which case you win.
- Or, your current roll is not greater than your previous roll, in which case you lose.
For example, when :
- Rolls : Win
- Rolls : Lose
- Rolls : Lose
- Rolls : Win
Find a formula to find the probability of winning for any given .
Today is the birthday of our beloved Srinivasa Ramanujan Aiyangar and also India's National Mathematics Day! (not a coincidence!). But coincidently, it is my AoPS account's birthday too! (I swear it was a coincidence!). My account has turned exactly year today and has posts as of now (excluding this) and has received upvotes.
And as a result I am quitting AoPS (atleast as of now)
Why?
I have a big exam upcoming in the next months and it is probably the biggest exam I have ever given. So yeah I need to prepare for that and I think I should not spend much time on AoPS anymore as of now. I will probably join AoPS after months. I know no one asked but just in case you guys may be surprised as to why are there no more billion HSM posts per day.
I will probably update my blog(?).
So yeah this concludes this post(?). I probably have not written whatever I wanted to but AoPS has been basically the website I have been the most active on for the past year so leaving this hurts. (Not like I am going for forever lol)
Anyways as promised here are a "few" (not so original) questions.
Questions
Geometry:
Here is a collection of geometry problems and solutions for new ideas:
Q1
In a triangle , the altitude and the median divide into three equal parts. If , then the nearest integer to is?
S1
IMAGE . as .
Using Internal Angle Bisector Theorem in . , or, .
Using Pythagorean Theorem in , , or, .
Using Pythagorean Theorem in , .
Thus .
Thus the closest integer is .
S1 by lbh_qys
Let be the circumcenter, then , which indicates that ,, and are colinear. Therefore, or . However, when , and coincide, and the angle is not trisected. Thus, , and triangle is a right-angled triangle. Consequently, the altitude divides the angle into and , which implies the triangle is a right-angled triangle with angles ,, and . Therefore, , and the closest integer is .
Q2
The sides of a triangle satisfy the relations and . Then the measure of , in degrees, is?
S2
Q3
Let be a triangle in which . From the vertex , draw the altitude to meet at . Assume that and . Then equals?
S3
Let . (Pythagorean Theorem). Thus and (Pythagorean Theorem).
Q4
Let be a square of side length . Let be points in the interiors of the sides , respectively, such that and intersect at right angles. If then find the length of .
S4
IMAGE
We rename the points as per the diagram.
Let and .
Then, as , and and .
Thus the required length is .
S4 by Mathzeus1024
Let the points be located in the plane. If , then:
(i).
If , then (ii).
Finally, .
Q5
Let be a point inside a triangle with . Let and be the images of under reflection in and respectively. The distance between the circumcenters of triangles and is?
S5
Let and and . Assume then and . Observe that the circumcenter of is just . Observe that the circumcenter of is just . Thus the distance is just the circumradius or .
Q6
Three circles of radii and units respectively touch each other externally in the place. The circumradius of the triangle formed by joining the centers of the circles is?
S6
Observe the triangle formed is a right angled triangle thus the circumradius is .
Combinatorics:
Here is a collection of combinatorics problems and solutions for new ideas:
P1
Connie finds a whiteboard that has magnet letters spelling MISSISSIPPI on it. She can rearrange the letters, in which identical letters are indistinguishable. If she uses all the letters and does not want to place any Is next to each other, how many distinct rearrangements are possible?
S1 (Gap Method)
We first arrange the M,P,S and later put the Is. Ways to arrange the M,P,S. We have places to choose form and way to arrange the Is in it. Thus the final answer is .
Q2
Carson is planning a trip for people. Let be the number of cars that will be used and be the number of people per car. What is the smallest value of such that there are exactly possibilities for and so that is an integer, , and exactly one person is left without a car?
S2
Ofcourse . Now . As there are possible values for (and the corresponding values of ) thus the total number of factors of is . can be of the form or . We bash to find the least is possible in the second case with and thus resulting the final in being .
Comment
Observing was quite natural. Now the main thing is observing that has factors. This gives us an idea that whenever in case of product and stuff with a certain quantity given, we should check for factors and stuff.
Functional Equations:
Here are a few problems of Functional Equations:
Q1
Let satisfy the equation . Then :
i) Prove that is bijective.
ii) Prove that is multiplicative
S1
Claim: is injective.
Proof: Say is not injective. Then such that .But a function can't give two distinct values, unless this is not true so must be injective.
Claim: is surjective.
Proof: Fix , or else .To obtain any just let .
Now, Thus is multiplicative.
Q2
Find all functions which satisfy for all :
for
S2
Note that and hence holds for all which easily extends to for all which is indeed a solution.
Q3
Find all functions such that
S3
The only constant solutions are and .
So let us from now look only for non constant solutions.
Let be the assertion
Let
and so and since is non constant; and so :
and so
implies which gives immediately , and which indeed is a solution.
implies which gives immediately and and which indeed is a solution.
implies which gives immediately which indeed is a solution.
Determine all integers that satisfy the following condition: For every integer k such that there always exists a positive integer that is divisible by n and .: sum of elements of