## Apollonius geometry iphone app: free to first 5 commenters

**[ Update: All 5 free apps are gone but you can buy one for $3.99 at Itunes. ]**

Adolfo Rodriguez has created an iPhone/iPod Touch/iPad interactive geometry app called Apollonius. It can be described as a simplified touchscreen version of "Cabri" or "The Geometer's Sketchpad."

Adolfo is giving away five copies of the app.

Apollonius is the first (and so far the only) Interactive Geometry Software (IGS) for the iPhone and iPod Touch. It allows you to make geometric constructions (such as those made using a compass and straightedge/ruler) and move their parts smoothly using the device's touchscreen.

Apollonius was inspired by similar software for personal computers, such as Cabri and The Geometer's Sketchpad.

An example of a simple construction that can be made with Apollonius is a triangle with its medians, heights, and angle bisectors. Moving the vertices of the triangle will then simultaneously move the medians, heights and angle bisectors accordingly.

Apollonius remembers your last construction when the program is closed. It also allows you to ZOOM and SCROLL your construction, providing a very large virtual screen.

New versions will start appearing soon with great new features, so make sure to visit this page once in a while. Updating to a new version is FREE once you have bought the app!

About IGSs: Interactive geometry environments are powerful tools in the development of problems and conjectures in planar geometry. They have also proven to be very useful as educational tools.

Here's a link to the app.

If you're one of the first five people to leave me a comment I'll give you a code for a free download. Be sure to leave your email address in the email field in the comment form. And, if you like the app, be sure to rate it.

**[ Update: All 5 free apps are gone but you can buy one for $3.99 at Itunes. ]**

## 2nd blog post at Equalis

Here is the second blog article in which I stumble around the Math blogosphere (blathosphere) and note interesting things I find.

In that article I share links to a few interesting exploration posts (my favorite kind) and I give more information about the clever clock conundrum that no one responded to.

## Wild about Math bloggers

Check out my first blog article at Equalis.

Today begins my voyage into the Math blogosphere, which I believe Vlorbik first named the "blathosphere.” My aim with this weekly series is to highlight the Math-related blog posts I find particularly interesting. This is no small task. There are tons (but not uncountably many) very interesting Math blogs out there. There are certainly too many for me to keep up with. Plus, I don't have a clear set of criteria for determining if a blog or a blog post is interesting so I can't go through some checklist and make an objective evaluatbion. Basically, this is a right-brain exercise. If I like it I'll tell you about it. (More)

## Couple of carnivals and a clever clock conundrum

Two Math carnivals have recently been published:

- The 68th Carnival of Mathematics at +plus magazine
- The 2nd Mathematics and Multimedia Blog Carnival at the Mathematics and Multimedia Blog.

Now, here's a challenging adaptation of a problem I recently discovered. I won't reveal the source till later to not give away the problem.

There's something interesting about the time 2:26 and other times of the day. This interesting thing can be seen over 100 times per day. What is the property and exactly how many times does it occur in a day?

## Equalis Math community goes into beta

On August 2nd the Equalis Math community went from super-secret mode into a public beta. I'm super-excited to be part of a community dedicated to Math.

From the Equalis About Page:

Equalis is the innovative on-line destination for the mathematics community. It provides the most vibrant and far reaching math-centric community on the internet, enabling the free flow of ideas, cutting-edge research, open source software, problem solving, open innovation and job opportunities for individuals and organizations with a common interest in math and math-centric endeavors.

Equalis provides a number of community elements: blogs, groups, forums, and a calendar of Math-related events.

## Review: 101 Things Everyone Should Know About Math

A friend, who later started a home organization business, once told me that she believed everything we own should be beautiful or useful. That pretty well sums up my feelings about Math. 101 Things Everyone Should Know About Math provides a compilation of problems in the realm of "useful."

"101 Things" has questions in eight areas:

- Facts, Just Math Facts
- Health, Food and Nutrition
- Travel
- Recreation and Sports
- Economics
- Nature, Music and Art
- Miscellaneous
- Bonus Questions

Here's one problem from the "Health, Food & Nutrition" section:

A cake recipe says to put batter into two 8" round pans, but you don't have any. Of the following, which combination of pans will work best?

A. Two 8" square pans

B. One 9" square pan

C. One 9" x 13" rectangular pan

D. Three 8" x 4" rectangular pans

## Tonight: Calculus By and For Young People

Sorry for the late notice. I just got back from vacation. The event will be recorded for future viewing.

## Calculus By and For Young People

The free webinar is part of Maria Droujkova's Math 2.0 Interest Group series.

During the event, Don Cohen-The Mathman will have participants graphing things they have never done before and understand what graphing an equation or function means. He will show how to use his latest creation- A Map to Calculus, originally just a poster, but with the help of a former student Jonathan Storm, is now clickable! Each spot on the Map links to his student's work and sample problems from his books. We can also ask Don questions about his past and present work with students ages four and up, his books, and his books that were translated into Japanese and sold in Japan.

Donald Cohen has been teaching math for 56 years. He has taught in Junior HS, college, worked with Dr. Robert B. Davis for about 15 years with The Madison Project training teachers, and developed student lessons on PLATO, a computer-based program at the U of Illinois. He co-founded and taught in The Math Program, a private program, tutoring children since 1976.

More information is here.

## What do you call the son of your mom’s cousin?

I don't know about you but I get a headache trying to figure out the proper term for how distantly related people are related. Lifehacker tells us that Wolfram Alpha does all the heavy lifting for you:

From Lifehacker:

What do you call the son of your mom's cousin? How about the husband of your mother's uncle's daughter? Type how you're related into Wolfram Alpha's computation engine, and it returns the relationship—first cousin once removed, in that last example.

Not only do you get a sketch of the family tree when you enter something like "great-uncle's son's daughter," but you get a quick chart explaining just how related you are to the person you're describing, in a "blood relationship fraction." You may now proceed to whittle down your holiday card list, as well as impress everyone with your proper genealogical naming at the family reunion.

More detail is available at the Wolfram Blog article, My Cousin’s Cousin’s Niece’s Grandfather Said to Just Ask Wolfram|Alpha.

## An evil twist on an old idea

From OhGizmo!

This gadget is pretty evil. It's an alarm clock that won't turn off until you solve an arithmetic problem. If you're not awake enough some morning to disarm the alarm, take solace in this quote from the OhGizmo! article:

... I wouldn’t actually worry about it becoming too annoying since I’m sure it will work with that age old equation; alarm clock + wall = silence.