Israeli 10th-Grader Stumbles Upon New Geometric Theorem


Tamar Barbi from Hod Hasharon is only in the 10th grade, but she has already chalked up an impressive achievement: developing a new geometric theorem.

Yael Branovsky reports for Israel Hayom that Barbi, who is studying mathematics on the highest matriculation track offered in Israel, discovered while doing her geometry homework that the theorem she was using to solve one of the problems on her homework didn’t actually exist.

“I checked with my teacher, Sean Gabriel-Morris, I asked relatives abroad who are involved with mathematics, and I consulted my parents, and [then] I realized that the theorem really didn’t appear anywhere, even though it’s very logical and basic.”

According to the new “Three Radii Theorem,” if three or more lines extend from a single point to the edge of a circle, then the point is the center of the circle and the straight lines are the radii.

Branovsky reports in Israel Hayom that Gabriel-Morris, a former chef who retrained as a math teacher, worked with Tamar to research the subject and helped her develop the new mathematical theorem, proving that it could serve as an easy, convenient solution for many geometry problems. The teacher-student team sent the theorem along with proof to a mathematician from the Massachusetts Institute of Technology, who became excited and wrote back that “it’s good to see how Tamar’s theorem provides elegant proof for other important mathematical theorems.” The proof was also sent to math lecturers at the University of Haifa, and Barbi and Gabriel-Morris were invited to give a lecture on it to some of the top math instructors in Israel.


{ Israel}


  1. So we aren’t settling for photos of Hillary…. Now, the “Torah” website Matzav is publishing the photos of young women such as the ping pong star from Lawrence and this math genius from Israel.

    Why the gratuitous pictures? Has the standard been lowered? Will the Yated start publishing these pictures as well?

    I am sorry for sounding over-the-top but these forays over the line of acceptability must be nipped in the bud. I would love to hear your editorial response.

    • Quite frankly matzav is in the right. Its you who is breaching the mesorah towards the direction of meshagas!. Learn some jewish history

    • Why the gratuitous pictures?

      Because it is relevant to the article

      Has the standard been lowered?
      No, the opposite they have been raised! Most of use here have succesfully quashed any yetzer harah associated with the above picture. That it casues any stumbling block for you is your concern. Here our standards are higher than that.

  2. The theorem is over 2300 years old. See Euclid’s Elements, Book 111, Proposition 9:

    If a point is taken within a circle, and more than two equal straight lines fall from the point on the circle, then the point taken is the center of the circle.

  3. there is a glaring omission the way the theorem is presented- it should read””if 3 or more lines of equal length etc. “””

  4. To w: there’s not even a hint of pritsus here. What is the halachic source of the stringency you are trying to impose?

  5. No, no, no! It’s DMV Driver’s Guide book 1, page 19, section C……………. What were we talking about?