Puzzleup 2021 (1) EQUILATERAL TRIANGLES - 拼圖

題目網址: https://www.puzzleup.com/2021/
https://www.puzzleup.com/2021/puzzle/?1
答題時限: ９月２日７ＰＭ－比賽結束（約11月９日）
加分時限: ９月２日７ＰＭ－９月７日６：５９ＰＭ

答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　

◆EQUILATERAL TRIANGLES

https://www.puzzleup.com/2021/img/puzzle/2021/01.jpg

How many equilateral triangles can be obtained by joining 19 points shown in
the figure?

-All pairs of points are equidistant.
-Three possible triangles are drawn as an example.

https://www.puzzleup.com/2021/img/puzzle/2021/01s.jpg

圖中的 19 個點互相連結可以得出多少個正三角形？

- 每對相鄰的點距離都相等。
- 其中的三種畫法如上圖所示。

--
'You've sort of made up for it tonight,' said Harry. 'Getting the
sword. Finishing the Horcrux. Saving my life.'
'That makes me sound a lot cooler then I was,' Ron mumbled.
'Stuff like that always sounds cooler then it really was,' said
Harry. 'I've been trying to tell you that for years.'
-- Harry Potter and the Deathly Hollows, P.308

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