What exactly is π (pi) ?

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Subject: GCSE Maths
Last updated: 12/03/2009
Tags: did you know?, gcse maths
GCSE Maths

Most students are terrified of the Greek letter "π" (spelt "pi" and pronounced like the word pie). The fear partially originates from the "strangeness" of the Greek letter "π" and also partially due to its mathematical attributes.

On closer analysis, however, the fear is often easily dispelled -  when the simple and  everyday reality behind "π" is revealed. The confusion and fear are further compounded by the fact that the "π" is introduced to the student when s/he has just managed to work out what "x" is!

Of course both "x" and "π" are letters - albeit of two different languages. However, the similarity ends just there, as often in mathematics the "x" is a variable and therefore does NOT have a fixed value. And "π" of course is a Constant! This means that it does NOT change. Never!

And so, what then is this "π” ? Does it have any particular flavours, for instance? Is it chicken and mushroom or steak and kidney, for example?

No! Mathematically speaking, it has an unchanging value of 22/7 as an improper fraction or 3.142 in decimal notation.

After all that, you still don't know what "π" is? Ok, listen up carefully! Here we go: If a bicycle wheel had a radius of 7 inches then its rim would be of 44 inches in circular length. That is, if you were to flatten the rim out into a long metal rod, then it would measure 44 inches in length, without stretching the metal of course!

Similarly, a 14-inch radius would give a 88-inch rim, and a 70-inch radius would give a 440-inch rim! And you get the picture, right? The rim is what we in mathematics fondly call the Circumference.

Clearly the ratio between the circumference and radius is 22:7 or just 22/7. If you compute this using a calculator, you would obtain 3.142...... . This fraction is shortened to just: "π".

The value and knowledge of "π" is of vital importance in Mathematics and in all areas of Science; from calculations in Spatial Astronomy to Inter-atomic force fields.

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Jay GCSE Maths Tutor (Watford)

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Hi, My name is Jay and thanks for visiting my profile today.
I am probably the only resident tutor in Radlett, specialising in Mathematics, Physics and Chemistry up to A/ Levels



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