# IntMath Newsletter: Golden spiral, $0 math e-books, CDF format

By Murray Bourne, 05 Sep 2011

5 Sep 2011

In this Newsletter:

1. Golden Spiral

2. Math e-Books for $0

3. 13 yr-old designs efficient solar collectors using Fibonacci and trees

4. Wolfram's new Computable Document Format

5. Math Puzzle: Solution and new one

6. Friday math movies

7. Final thought: Powerful weapon

## 1. Golden Spiral

**Suitable for: **This is an interesting article because there are several important math concepts involved. If you have some basic understanding of trigonometry and exponentials you will get more out of it.

Golden Spirals involve a lot of interesting math, from exponential curves to polar coordinates, tangents to a curve and approximating curves. |

## 2. Math e-Books for $0

**Suitable for: **Everyone who likes a freebie!

Here's a collection of free (or cheap), mostly good quality math text books in PDF format. |

## 3. 13 yr-old designs efficient solar collectors using Fibonacci sequence and trees

**Suitable for: **Everyone.

This is a useful discovery by a 13 yr-old, using math and good observation skills. Trouble is, it turned out to be not as efficient as claimed! (See the comments.) It also turned out to be a hoax... |

## 4. Wolfram's new Computable Document Format and Online Conference

We've had PDF format for some time now.

Wolfram, developers of Mathematica and the brilliant Wolfram|Alpha, have released a new type of document which can include interactive animations of math concepts.

The documents it produces are free, but you need to purchase Mathematica if you want to produce such documents. But never mind, there's still a lot of value in this. You'll need to download a small file in order to view, and play with, the CDF files.

Interactive Whiteboard users - this is for you!

Go to Computable Document Format

**Wolfram Mathematica Online Conference**

Wolfram is also hosting a free Mathematica Virtual Conference on Sep 26th (for US time zone) and on 27th Sep (Europe time zone - also good for Asia).

For those new to Mathematica, the "Discover Mathematica" session will be good. There's also a session on "Applying Mathematica in Industry and Research" and for the teachers, "Applying Mathematica in Education".

I'll be attending the 27th Sep session - say hello if you see my name in the participant list!

Information and free registration: Wolfram Mathematica Virtual Conference 2011

## 5. Math Puzzle - solution and new one

Last newsletter, the math puzzle was:

If the end of the world should come on the first day of a new century, what is the probability that it will happen on a Sunday?

While it seems the probability should be 1/7, it isn't!

The first day of a century can never fall on a Sunday; nor on a Wednesday or a Friday. See here for an explanation.

**New puzzle: **

A business man works on the 10th floor of an office building and always takes the elevator down to ground level at the end of the day.

Yet every morning he only takes the elevator to the 7th floor and walks up the stairs to the 10th floor, even when he is in a hurry.

Why? (You can answer here.)

## 6. Friday math movies

I have a back-log of math movies this Newsletter. Enjoy!

## (a) Miss USA 2011 - Should math be taught in schools?
This is hilarious - or very disturbing - depending on your point of view. Friday math movie: Miss USA 2011 - Should math be taught in schools? |

## (b) Wireless data from every light bulb
Here's a great idea - get your wireless data more efficiently and safely. |

## (c) How algorithms shape our world
Done a Google search today? You've used an algorithm that is helping to change the world. |

## 6. Final thought β powerful weapon

Sadly, a lot of students (and some teachers!) mope around complaining about how everything "sucks" and is "sooo boring". But the world is full of so many great and interesting things - we only have to look - and enjoy!

Ferdinand Foch, French soldier and military theorist of the late 19th century, could have been talking to jaded students when he said:

The most powerful weapon on earth is the human soul on fire.

[Ferdinand Foch]

Until next time, enjoy whatever you learn.

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