A love letter from the math teacher

r=a( 1-sinθ)

The thirteenth love letter

Descartes was born in France in the17th century. He made great contributions to later generations. He was the first person to invent coordinates, but he was poor all his life. Until he was 52 years old, he was still unknown.

At that time, the Black Death prevailed 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 them found that his accent was not Swedish. She was very curious about Descartes, so she went up to him and asked him ... where are you from? France "What do you do?" "I am a mathematician." This girl 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 Descartes say his name, she felt quite interested, so she invited Descartes back to the palace. Descartes became her math teacher, and gave her life's research to Christine. And Christine's math is improving day by day. At that time, Cartesian coordinates were only understood by Descartes. 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! Descartes was sentenced to death and Christine hanged herself. The king was afraid that his baby daughter was really unhappy, so he exiled Descartes to France and put Christine 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. So Christine never received a letter from Descartes ... Descartes sent the letter 13 when he was dying, and not long after it was sent ... he died. 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 could understand its meaning. The king thought ... Descartes was dying anyway, and the princess was depressed when she was under house arrest, so he gave the letter to Christine. When Christine received this letter, she was ecstatic. She is glad that her lover still misses her. She immediately began to study the secret of this line. It didn't take long to figure it out, using rectangular coordinates (note: it's actually polar 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 ... point d is the ratio of four intercepts.

Make the whole figure, which is the famous heart line!

Soon the king died, too, Christine.

Inherit the throne, immediately after the throne.

Send someone around Europe.

Descartes' trail,

It's a pity that ... everyone is dead,

Both talent and beauty?

It can be like a fairy tale