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for questions on one dimensional algebraic varieties over any field, including questions of moduli, and questions about specific curves.

2 votes
0 answers
166 views

Pascal theorem for three dimensions

A year ago I found the Pascal theorem for three dimentions as follows: Let $(C_1)$, $(C_2)$ be two conics on the same Ellipsoid, (or Hyperboloid, or Paraboloid). Let $A_1$, $A_2$, $A_3$, $A_4$, $A_5$ …
Đào Thanh Oai's user avatar
1 vote

Is it a new discovery on conic section?

Application of the theorem in post #1. I give a special case and give a proof as follows: Generalization of conjugate of a point: Let $ABC$ be a triangle, and $\Omega$ is arbitrary circumconic of $ABC …
Đào Thanh Oai's user avatar
13 votes
2 answers
2k views

Is it a new discovery on conic section?

I discovered a problem in plane geometry (there are some nice special cases) as follows: Let $ABC$ be a triangle and $\Omega$ be arbitrary circumconic. Let two points $A_b, A_c \in BC$, $B_c, B_a \in …
Đào Thanh Oai's user avatar
0 votes

Divide angles by coefficients relate to Fibonacci sequence

Locus equation of the point $O_1$, In Cartesian coordinates, as follows: $$x=\frac{1}{2}t\frac{t^2-3}{t^2-1}$$ $$y=\frac{1}{2}\frac{t^2+1}{1-t^2}$$ where $-1<t<1$ or the equation: $$x^2-y^2=\frac{2y^ …
Đào Thanh Oai's user avatar
0 votes
1 answer
208 views

Divide angles by coefficients relate to Fibonacci sequence

In the left Figure, consider a right triangle $OPA$ with $\angle {AOP} = 90^\circ$. Let $\ell$ be the reflection of $PO$ in $PA$ and $\ell$ meets $OA$ at $A_1$. Let $O_1$ be the center of the circle …
Đào Thanh Oai's user avatar