Changes

*The <math>pi</math>  is a mathematical constant with a value approximate to 3.14159.

*The <math>pi</math>  is a mathematical constant with a value approximate to 3.14159.

*It is denoted by the Greek letter <math>\Pi</math>.

*It is denoted by the Greek letter <math>\Pi</math>.

*<math>\Pi</math>  is commonly defined as the ratio of a circle's circumference C to its diameter d.  

*<math>\Pi</math>  is commonly defined as the ratio of a circle's circumference <math>C</math> to its diameter <math>d</math>.  

*So <math>\Pi =\frac {C}{d}</math>, the ratio <math> \frac {C}{d}</math>  is constant, and it is not considering the circle's size.

*So <math>\Pi =\frac {C}{d}</math>, the ratio <math> \frac {C}{d}</math>  is constant, and it is not considering the circle's size.

*<math>\Pi</math>  is a transcendental number and irrational number.  

*<math>\Pi</math>  is a transcendental number and irrational number.  

*Being an irrational number,<math>\Pi</math> cannot be expressed exactly as a ratio of any two integers .

*Being an irrational number,<math>\Pi</math> cannot be expressed exactly as a ratio of any two integers .

* But we can express as the fraction <math>\frac {22}{7}</math> is approximate to the  <math>\Pi</math> value , also no fraction can be its exact value.

*But we can express as the fraction <math>\frac {22}{7}</math> is approximate to the  <math>\Pi</math> value , also no fraction can be its exact value.

 

==Examples==

==Examples==