Descartes gave the first heart, which is r=a( 1-sinθ).

a = 1；

θ= 0:0.0 1:2 * pi；

r = a *( 1-sin(θ))；

polar(θ，r，'-r ')；

Descartes,/kloc-was born in France in the 0/7th century and made great contributions to later generations.

He was the first person to discover rectangular coordinates, but unfortunately he was down and out all his life.

He remained unknown until he was 52 years old.

At that time, the Black Death was prevalent in France, and Descartes had to flee France.

So he wandered to Sweden as a beggar.

One day, when he was begging in the market, a group of girls passed by.

One of the girls found that his accent was not Swedish.

She was very curious about Dika, so she asked him. .......

Where are you from? France.

What do you do? I am a mathematician.

The girl's name is Christine, 18 years old, and she is a princess.

Unlike other girls, she doesn't like literature, but she is keen on mathematics.

When she heard Decatur's name, she was very interested, so she invited Decatur back to the palace.

Dick Ade became her math teacher and gave Christine all her life's research.

And Christine's math is improving day by day. At that time, only Deckard and his teachers and students understood rectangular coordinates.

Later, there was a different feeling between them, and there was a noisy love between teachers and students.

The news reached the king's ears and made him quite angry!

Dick Ade was ordered to be executed, and Christine forced herself to hang herself.

The king is worried that his little daughter will be really unhappy.

So Descartes was exiled to France and Christine was placed under house arrest.

As soon as Descartes returned to France, he was infected with the Black Death and lay dying in bed.

Descartes has been writing to Christine in Sweden, but he was intercepted and confiscated by the king.

That's why Christine didn't get a letter from Descartes. .......

Descartes sent the letter 13 on his deathbed.

Shortly after he sent it ... he died of anger.

The content of this letter is only a short line. ......

r=a( 1-sinθ)？

After the king intercepted the letter, he opened it and found that it was not the usual love story.

Of course, the king couldn't understand this mathematical formula, so he called all the scientists in the city to study it.

But no one can figure out what this means.

The king thought ... Dikad would die anyway,

And the princess was unhappy when she was under house arrest, so she gave the letter to Christine.

Christine was overjoyed when she received this letter.

She is tall with her lover and still misses her. She immediately began to study the secret of this line.

It didn't take long to solve it, using rectangular coordinates.

When θ = 0, R = A (1-0) = A ... one point.

When θ = 90, r = a (1-1) = 0 ... point B.

When θ = 180, R = A (1-0) = A...c point.

When θ = 270, r = a (1+ 1) = 2a...d point?

A is the ratio of four intercepts, and point B is the origin (0,0). It takes a little imagination. Connect the four points A, B, C and D with an arc ... which is the famous heart line.

This is the secret mathematical formula between Descartes and Christine. Soon after, the king died and Christine succeeded to the throne.

Immediately after he ascended the throne, he sent people to all parts of Europe to look for traces of Decatur, but unfortunately ..... he died.

The legendary 13' s alternative love letter is still preserved in the Decatur Memorial Hall in Europe.