Skip to main content

All Questions

8 votes
2 answers
364 views

Convex cyclic hexagon $ABCDEF$. Prove $AC \cdot BD \cdot CE \cdot DF \cdot AE \cdot BF \geq 27 AB \cdot BC \cdot CD \cdot DE \cdot EF \cdot FA$

Convex hexagon $ABCDEF$ inscribed within a circle. Prove that $$AC \cdot BD \cdot CE \cdot DF \cdot AE \cdot BF \geq 27 AB \cdot BC \cdot CD \cdot DE \cdot EF \cdot FA\,.$$ I was thinking of ...
Vlad Zkov's user avatar
  • 755
0 votes
0 answers
81 views

For convex cyclic hexagon $ABCDEF$, show $AC\cdot BD \cdot CE \cdot DF \cdot EA\cdot FB \geq 27\cdot AB\cdot BC\cdot CD \cdot DE\cdot EF\cdot FA$ [duplicate]

Given a convex hexagon $ABCDEF$ inscribed in the circle, prove that $$AC\cdot BD \cdot CE \cdot DF \cdot EA\cdot FB \;\geq\; 27\cdot AB\cdot BC\cdot CD \cdot DE\cdot EF\cdot FA$$ ("$AC$" means the ...
user avatar
13 votes
2 answers
432 views

Polygons with 2 diagonals of fixed length (part two)

In this question of mine Polygons with two diagonals of fixed length I've presented the following particular polygon $P$ and I've asked the following question: is it possible to shorten one or ...
user avatar
1 vote
3 answers
2k views

Area of a cyclic polygon maximum when it is a regular polygon

My question: Let $n$ points $A_1, A_2,\ldots,A_n$ lie on given circle then show that $\operatorname{Area}(A_1A_2\cdots A_n)$ maximum when $A_1A_2\cdots A_n$ is an $n$-regular polygon.
Oai Thanh Đào's user avatar