A mathematics teacher named William Jones is credited with first using the symbol π in 1706 to represent the concept of the ratio between a circle's circumference and diameter. It had previously been ill-defined.
Continue ReadingPrior to Jones' usage of the π symbol, the ratio of a circle's circumference and diameter was known as "the quantity which, when the diameter is multiplied by it, yields the circumference." William Jones first used the symbol in his book, "Synopsis Palmariorum Matheseos, or A New Introduction to the Mathematics." Jones believed, but could not prove, that pi was irrational. In 1761, Johann Lambert first proved that pi was an irrational number.
Learn more about InventionsTo find the circumference of a circle, multiply the diameter by pi or double the radius times pi. Pi is an unchanging number that rounds off to 3.14.
Full Answer >To measure a circle's circumference, find the circle's diameter, then multiply the diameter by pi to find the circumference. If you only have the radius, multiply it by two to find the circle's diameter.
Full Answer >To calculate a circle's diameter from its circumference, one should divide the circumference by the constant pi, which is an irrational number approximately equal to 3.14159265358979.
Full Answer >If the circumference or the area of a circle is known, pi can be used to find the diameter and the radius of that circle. Likewise, if the radius or diameter is known, pi can be used to find out the circumference or the area.
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