Tim Corica
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tcorica.bsky.social
Tim Corica
@tcorica.bsky.social
820 followers 820 following 890 posts
Looooongtime math teacher. Believe in the dignity and respect of every human being.
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tcorica.bsky.social
Plus, it has a great cover, and was released just as we were working on vector fields in my MVC class.
November 7, 2025 at 5:02 PM
tcorica.bsky.social
To see the problem, you need to apply the definition of the derivative. You can write a derivative expression that assumes the curve is differentiable and then apply it to the (missing) point. The definition (below) requires a value for f(x) at x=4, but this does not exist. 1/2
Image of the limit expression that defines the derivative.
November 4, 2025 at 2:04 AM
tcorica.bsky.social
October 29, 2025 at 6:25 PM
tcorica.bsky.social
We were there - estimates at least 1500, maybe quite a bit more. Here's my poster:
October 18, 2025 at 7:33 PM
tcorica.bsky.social
The site even requires employers to have an EEOC pledge:
____ will not discriminate against apprenticeship applicants or apprentices based on RACE, COLOR, RELIGION, NATIONAL ORIGIN, SEX (INCLUDING PREGNANCY AND GENDER IDENTITY), SEXUAL ORIENTATION, GENETIC INFORMATION, OR BECAUSE THEY ARE AN INDIVIDUAL WITH A DISABILITY OR A PERSON 40 YEARS OLD OR OLDER.
September 6, 2025 at 9:30 PM
tcorica.bsky.social
This problem "rhymes" with an old favorite. A standard chess board has had two diagonally opposite corner squares removed. Can the remaining 62 squares of the board board be covered with 31 rectangular dominoes, each of which covers exactly two squares? 1/2
August 21, 2025 at 11:27 PM
tcorica.bsky.social
Yes, here's my example from three weeks ago.
August 18, 2025 at 6:29 PM
tcorica.bsky.social
The importance of teaching statistics. This is apparently a chart of "MEDIUM INCOME". #iTeachMath
August 7, 2025 at 10:18 PM
tcorica.bsky.social
Homer explains why we need to speak up *today*, not tomorrow!
August 7, 2025 at 2:59 PM
tcorica.bsky.social
Thanks for pointing out the shooter in the video - I missed this entirely. Despicable- not an accident!
Photo showing the smoke of the shot being fired at the Australian journalist, at quite close range.
June 9, 2025 at 2:36 AM
tcorica.bsky.social
Inspired by a post (now lost) from a few months ago, and from my reading of the excellent book, Vector, by Robyn Arianrhod, I decided to attack this using complex numbers/vectors. It has just a tad of geometry.

A Desmos sheet illustrates the work: www.desmos.com/calculator/h...
A proof of the result, 135 degrees, using complex number arithmetic and the dot product formula.
June 9, 2025 at 1:17 AM
tcorica.bsky.social
A "Towers of Hanoi" set works well for disks (and, if you look closely, washers), when it's not busy teaching recursion!
June 4, 2025 at 7:13 PM
tcorica.bsky.social
Reminder:
Bar graph of 50 states labeled "These are the US States Most Dependent on the Value of International Students" showing each bar at 100%.
May 24, 2025 at 5:42 PM
tcorica.bsky.social
My proposed modification to the Statue of Liberty inscription, based on this proposed legislation.

www.theguardian.com/us-news/2025...
May 17, 2025 at 12:44 PM
tcorica.bsky.social
You need a geometric property of a parabola to take the place of the "radius is perp to tangent line" for a circle. I think this might be the focus/directrix/reflection property, but it has many moving parts. I *think* the image does this (tho it's cryptic!). Maybe you can fix it.
Parabola with a point and its tangent line drawn, along with the directrix and focus.
May 3, 2025 at 10:49 PM
tcorica.bsky.social
Beautiful! Wow!

I see the equation on the work, but is there more information about how the equation translates to the image?

It reminds me a bit of Anders Hoff's Oribitals but the technique is completely different.

inconvergent.net/generative/
Wreath-like imaged produced using code.
April 28, 2025 at 5:07 PM
tcorica.bsky.social
Cheer up! Only 1361 days to go!
Cover of The Economist magazine showing a drawing of a beaten up bald eagle.
April 24, 2025 at 10:36 PM
tcorica.bsky.social
This question is described in a note after an old favorite problem in Brown/Robbins PC book, and the proof is implied. I've used it with students in PC-Honors in the past.
Photo of a page from Brown/Robbins. #33 through 38 prove that if a+bi is a root of a cubic, than a-bi must be a root. Then a note is provided saying that the proof can be generalized for any degree, and that it can be applied to a+root(b) and a-root(b).
April 24, 2025 at 9:05 PM
tcorica.bsky.social
Yes. Since 1960, income up 20%, rents up 64%, in the U.S.

www.apartmentlist.com/research/ren...
Graph showing income and rents 1960-2014, with income up 20%, rents up 64%.
April 22, 2025 at 1:05 PM
tcorica.bsky.social
Lovely! And the rubber band lays flat!

I like mine espresso style.😀
April 21, 2025 at 2:13 PM
tcorica.bsky.social
Hi, Erick. I like to start with 1-2 non-continuous optim problems to clarify the idea of optimization more generally. Eg, manually find an optimal value over the integers for some prob. I also often do a little LinProg problem, letting them work intuitively rather than providing an a algo.
1. A carpenter and her partner specialize in building handcrafted chairs and tables from rare wood. They are sold at different prices, with each chair being sold for $50 and each table for $75. Situation 1: Chairs require 2 hours of work, and tables require 1 hour of work. The carpenter and her partner devote up to 80 hours per week (total) to their work. How many chairs and how many tables should they produce each week in order to maximize their income? Justify this. Situation 2: In this part, assume that they are willing to work overtime past 80 hours, so this is not an important limitation. However, the rare wood is limited in supply. They can get only 100 cubic feet of wood each week. Chairs take one cubic foot, but each table requires two cubic feet. Assuming the prices are the same as before, find how many chairs and how many tables they should produce each week. Justify this. Situation 3: Assume that the labor is limited to 80 hours and the total amount of wood is limited to 100 cubic feet. Assuming the prices are the same as before, find how many chairs and how many tables they should produce each week. Justify your conclusion. Generalizing: Illustrate the situations above graphically, and try to generalize the process of solving problems like these. In each situation above, we assumed the selling prices remained the same. Consider how changes in the selling prices could lead to different results for each situation.
April 21, 2025 at 1:54 PM
tcorica.bsky.social
@decodingfoxnews.bsky.social

Nicole Hemmer, in New Republic.

Thanks for what you do!
There are ways that authoritarian governments keep control over their people, even during periods of extreme economic crisis—and, in fact, are able to consolidate their power and their propaganda instruments in periods of extreme economic crisis. So that’s why Fox News is particularly important to watch in the months and the years ahead: They are a key source of message control for a government that is trying to control basically everything.
April 11, 2025 at 1:43 PM
tcorica.bsky.social
Is today the day the T admin ignores the courts?

Friday's ruling by Judge Xinis: "2. Defendants are hereby ORDERED to facilitate and effectuate the return of Plaintiff Kilmar Armando Abrego Garcia to the United States by no later than 11:59 PM on Monday, April 7, 2025"
NY Times headline: Judge Calls Mistaken Deportation of Maryland Man a ‘Grievous Error’ Judge Paula Xinis, who has ordered that the Trump administration return the man, Kilmar Armando Abrego Garcia, by Monday, also rejected a request to pause that order.
April 7, 2025 at 2:00 PM
tcorica.bsky.social
We were planning on going to Princeton, and then a new event popped up in our little town of Monroe and we decided to support them there. It was probably 600 (some said 1000), very engaged, despite the rain!
April 6, 2025 at 3:21 PM
tcorica.bsky.social
Monroe, NJ protest. I'd estimate 600, but others said 1000. Lots of "This is my first time at a protest". Favorite sign seen: "Cory sent me!".
April 5, 2025 at 6:15 PM