Search

## Search Loci: Convergence:

Keyword

Random Quotation

My work has always tried to unite the true with the beautiful and when I had to choose one or the other, I usually chose the beautiful.

In an obituary by Freeman J. Dyson in Nature, March 10, 1956.

See more quotations

# A Disquisition on the Square Root of Three

## Continued Fractions

A "standard" sequence of continued fractions for approximating $$\sqrt{3}$$ follows.

$1+\frac{2}{2}=2=2.000000$

$1+\frac{2}{2+\frac{2}{2}}=\frac{5}{3}\approx 1.666667$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}=\frac{7}{4}=1.750000$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}=\frac{19}{11}\approx 1.727273$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}=\frac{26}{15}\approx 1.733333$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}}=\frac{71}{41}\approx 1.731707$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}}}=\frac{97}{56}\approx 1.732143$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}}}}=\frac{265}{153}\approx 1.732026$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}}}}}=\frac{362}{209}\approx 1.732057$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}}}}}}=\frac{989}{571}\approx 1.732049$

$1+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2+\frac{2}{2}}}}}}}}}}}=\frac{1351}{780}\approx 1.732051$

These approximations give the same fractions as the Greek ladder table. Thus, it seems fair to declare that the continued fraction method of estimating $$\sqrt 3$$ ties the Greek ladder method.

Pages: | 1 |  2 |  3 |  4 |  5 |  6 |  7 |

Wisner, Robert J., "A Disquisition on the Square Root of Three," Loci (June 2010), DOI: 10.4169/loci003514