520 or I love you day
Today is May 20th which in Chinese is known as 520 day, these numbers are pronounced Wu 五 Er 二 Ling 零. It is used to confess love since it has a similar sound to "I love you" or Wo 我 ai 爱 ni 你.
In the language of mathematics "I love you" can be written as " ρ=a(1-sinθ) ". This polar equation when graphed will give the curve shown below called a
Cardioid. Aptly named since it derives from the Greek word καρδία (cardia) which translates to "heart".
(Graph source)
"The name cardioid was first used by de Castillon in
Philosophical Transactions of the Royal Society in 1741. Its arc length was
found by la Hire in 1708. There are exactly three parallel tangents to the cardioid with any given gradient. Also,
the tangents at the ends of any chord
through the cusp point are at right angles The length of any chord through the cusp
point is ."
Weisstein, Eric W. "Cardioid." From
MathWorld--A Wolfram Web …
