Incentric Ratio

Geometry Level 5

A non-isosceles triangle A B C ABC has incenter I I and the incircle touches B C BC , C A CA and A B AB at D D , E E , and F F . Let E F EF cut the circumcircle of C E I CEI at P E P \not= E . A line l l is drawn parallel to A B AB through P P . It cuts B C BC at X X . Find the value of B X X C \frac{BX}{XC} to 3 decimal places.


The answer is 1.000.

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1 solution

Maria Kozlowska
Feb 9, 2017

C E I = 90 O \angle CEI = 90 \Rightarrow O is a midpoint of C I CI where O O is circumcentre of C E I \triangle CEI .

Let Z Z be the midpoint of A C AC . Then O Z I A OZ \parallel IA . I A F E O Z F E IA \perp FE \Rightarrow OZ \perp FE . Let G G be a point of intersection of the extensions of F E FE and O Z OZ . Then E O P \triangle EOP is isosceles and G G is a midpoint of E P EP . Triangles A F E , E P Z AFE, EPZ are similar therefore P Z A B PZ \parallel AB therefore X X is a midpoint of B C BC .

Ah! I missed this b/c I clicked the "discuss solution" instead of the "SUBMIT" after entering the answer. LOL Mine is a bit different with less constructions but I liked your construction. +1

Vishwash Kumar ΓΞΩ - 4 years, 3 months ago

@Calvin Lin I would like to request you to add this as a solution. @Neel Khare 'Would like to see your tricky "trigy" solution too.

Vishwash Kumar ΓΞΩ - 4 years, 3 months ago

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Oh yes Actually mine is simple Very simple I have just shown that area of triangle ABP = 1/2 area of triangle ABC

A Former Brilliant Member - 4 years, 3 months ago

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I would be interested in reading your solution. Could you please post it? Thanks.

Maria Kozlowska - 4 years, 3 months ago

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@Maria Kozlowska Definitely Let me write it down I will post it soon

A Former Brilliant Member - 4 years, 3 months ago

@Rohit Camfar @Maria Kozlowska This is actually from the Korean team selection test 2016

A Former Brilliant Member - 4 years, 3 months ago

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