Math Is Fun Forum

Hannibal lecter

Member

Registered: 2016-02-11

Posts: 392

conflict in some Euclid of elements book

hi,
in this link :

https://mathcs.clarku.edu/%7Edjoyce/java/elements/bookVI/propVI4.html

I Quote from : Now, since the angle DCE equals the angle ABC, DC is parallel to FB. Again, since the angle ACB equals the angle DEC, AC is parallel to FE.
depending on the right link : (I.28) as you can see on the page in the right that blue link
that leads to proposition 28 book I (https://mathcs.clarku.edu/%7Edjoyce/java/elements/bookI/propI28.html)

the problem he is saying DCE equals the angle ABC but it's not like proposition 28 said
because DCE and ABC is corresponding angels which the proposition 28 didn't mention anything about it just talk about alternate angels,
so how cold they depend on something that in its turn didn't mention them or talk about!!!
please explain it's very necessary to me

Last edited by Hannibal lecter (2024-01-25 09:57:59)

---

Wisdom is a tree which grows in the heart and fruits on the tongue

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: conflict in some Euclid of elements book

Parallel lines are cut by a transversal in equal angles arises first in book 1 proposition 28.  That is the theorem that is being used here.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob