# Curves

### Quadratrix of Hippias

Cartesian equation:
$y = x \cot(πx/2a)$
Polar equation:
$r = 2a \theta /(π\sin( \theta ))$

### Description

The quadratrix was discovered by Hippias of Elis in 430 BC. It may have been used by him for trisecting an angle and squaring the circle. The curve may be used for dividing an angle into any number of equal parts.

Later it was studied by Dinostratus in 350 BC who used the curve to square the circle.

Hippias of Elis was a statesman and philosopher who travelled from place to place taking money for his services. Plato describes him as a vain man being both arrogant and boastful. He had a wide but superficial knowledge. His only contribution to mathematics seems to be the quadratrix.

Other Web sites:

Xah Lee
M D Huberty

### Associated Curves

Definitions of the Associated curves