# SACRED GEOMETRY: Lunes of Hippocrates 470BC

- Posted by Jain 108
- Categories Mathematics, Sacred Geometry
- Date June 12, 2021
- Comments 2 comments

Euclid lived around 300BC. Of the 13 Books of the Elements written, his was not the first, he wrote the 4^{th} book. It was Hippocrates of Chios or Kos Island of Greece (born circa 470BC) who wrote the 1^{st} Book. The 2^{nd} and 3^{rd} are missing.

We know from Euclid’s proof in Proposition V1.31 (Book 6, Proposition 31) that the sum of the square area of the hypotenuse is equal to the combined sum of the 2 smaller sides. He showed that even the sum of rectangles obeyed this law. This law is anchored in the familiar realization that the Pythagorean 3-4-5 Triangle proves that 3×3 + 4×4 = 5×5.

Begin with any semi-circle with diameter AB and point C on its circumference. Draw the triangle ABC. It was a well known geometrical fact that a triangle drawn in a semi-circle is always a right triangle, ie: it is 90 degrees. Draw 2 more semi-circles on the other 2 sides of the triangle.

The semi-circle on AB includes the shaded areas of parchment brown and red sections S1 and S2. Each of the other 2 smaller semi-circles include a region shaded both with red (S1 or S2) and grey (L1 or L2). Since ABC is a right triangle, the semi-circle on the hypotenuse is equal to the sum of the other 2 semi-circles.

As both the semi-circle on the hypotenuse and the sum of the other 2 semi-circles include the red regions, therefore, by subtracting the red regions, we can conclude logically that the 2 grey regions equal the area of the right-angled triangle shown in light parchment colour.

This is an astounding and ancient revelation, that the areas of straight-lined polygons equal the areas of curved moon-like geometries called lunes.

ie: The famous Lunes of Hippocrates is the first solved area between curved lines.

Jain 108

## 2 Comments

Lunes of Hippocrates 470BC … that was fun … interesting … I can see my little momma in that context … moving in/out/through the geometric grid …:

https://tahomahome.weebly.com/mommas-homepage.html

Thank you for sharing Jain108!!

Cheers to you,

ka

That is interesting indeed, but it should file under the 400-odd proofs of the “Pythagoras” Theorem. For it is not a rationale as yet, it does not tell us why the theorem works. Again from the 3-4-5 triangle, the true rationale may be deduced, including that of Thales’s Fifth Theorem. Of course, both ideas hail from ancient Egypt, where the smart young Greeks from wealthy families were introduced to them. But these machinations were never put to paper, as far as is now known. My material, including the elusive ancient Egyptian circle-to-square ratios I mentioned before, is not published thus far. So, if you are interested, please let me know. Best regards, JGC.