# SOME INTERESTING FACTS OF CIRCLE

## Circles of Class 9

### Is a straight line is a circle with an infinite area…..

In situations where there are no navigational clues – such as a snowstorm or thick fog –

humans always end up going around in circles.Research carried out in 2009 by the Max Planck Institute for Biological Cybernetics in Tübingen had volunteers set down in a particularly empty bit of the Sahara or the dense, flat Bienwald Forest in south-west Germany and tracked them using GPS. When the sun or moon was out, they were perfectly capable of walking in a straight line. When it wasn’t, they started to walk in circles, crossing their own path several times: the average diameter of the circle they walked was only 66ft (20m). It suggested that we have no instinctive sense of direction.

### Life of pi –facts about pi

The one mathematical constant most non-geeks know is pi or π, the Greek letter P. This is obtained when you divide a circle’s circumference by its diameter. π is approximately equal to 3.14159265358979, but it’s an irrational number (i.e. it cannot be exactly expressed as a fraction or ratio) so the digital sequence never ends or repeats itself. Other irrational numbers including the so-called “golden section” can only be expressed as square or cube roots; these are called “surds” or deaf numbers.π was known by ancient geometers such as Archimedes (287-212BC) but it wasn’t called π until 1706, when the Welsh mathematician William Jones used the letter to stand for “perimeter”.When you divide a circle's circumference you get PI! the best number on earth!!!3.14159265358979.

- If a group of army ants gets separated from the main foraging party, they can lose the pheromone track and begin to follow one another. They form a continuously rotating circle and keep going until they die of exhaustion.

### Ant circles

If a group of army ants gets separated from the main foraging party, they can lose the pheromone track and begin to follow one another. They form a continuously rotating circle and keep going until they die of exhaustion.

### Divination circles

Gyromancy is a form of divination in which a person walks in circles until they fall over through dizziness. The position one falls in is then used to interpret the outcome of future events.A human has NO instinctive sense of directon so if there are absolutely no navigational clues, we will naturally walk in Circles and Circles!!!

### Stone circles

The most famous henge – an oval area enclosed by a bank and an internal ditch – is Avebury, in Wiltshire. The nearby ancient stone circle of Stonehenge isn’t, strictly speaking, a henge because its ditch runs outside its bank.

The word henge was given its precise modern meaning by Thomas Kendrick, Keeper of British Antiquities at the British Museum, in 1932. For centuries, any stone circle or ritual site was called a henge in imitation of Stonehenge. The word had long since lost its meaning in Old English, which was “hanging place” (either in the sense of “gallows” or “precipice”).

Kendrick used it to mark out a particular style of circular monument which occurred all over the British Isles but not in the rest of Europe. But, by defining it so precisely, he excluded Stonehenge itself.