Difference between revisions of "Mock AIME 1 2006-2007 Problems/Problem 10"

Line 4: Line 4:
 
==Solution==
 
==Solution==
 
{{solution}}
 
{{solution}}
 +
 +
 +
Radius <math>a=\frac{3}{7}</math>, radius <math>b=\frac{6}{11}</math>, radius <math>c=\frac{2}{5}</math> and <math>r=1</math>, see picture.
 +
 +
Given <math> \frac{r}{a}+\frac{r}{b}+\frac{r}{c}=\frac{m}{n} =\frac{20}{3}</math>, so <math>m+n=23</math>.
 +
[[File:C:\Documents and Settings\Eigenaar\Mijn documenten\Documenten van Valère\Mock06-07,10.PNG]]
  
 
----
 
----

Revision as of 16:27, 19 December 2012

Problem

In $\triangle ABC$, $AB$, $BC$, and $CA$ have lengths $3$, $4$, and $5$, respectively. Let the incircle, circle $I$, of $\triangle ABC$ touch $AB$, $BC$, and $CA$ at $C'$, $A'$, and $B'$, respectively. Construct three circles, $A''$, $B''$, and $C''$, externally tangent to the other two and circles $A''$, $B''$, and $C''$ are internally tangent to the circle $I$ at $A'$, $B'$, and $C'$, respectively. Let circles $A''$, $B''$, $C''$, and $I$ have radii $a$, $b$, $c$, and $r$, respectively. If $\frac{r}{a}+\frac{r}{b}+\frac{r}{c}=\frac{m}{n}$ where $m$ and $n$ are positive integers, find $m+n$.

Solution

This problem needs a solution. If you have a solution for it, please help us out by adding it.


Radius $a=\frac{3}{7}$, radius $b=\frac{6}{11}$, radius $c=\frac{2}{5}$ and $r=1$, see picture.

Given $\frac{r}{a}+\frac{r}{b}+\frac{r}{c}=\frac{m}{n} =\frac{20}{3}$, so $m+n=23$. File:C:\Documents and Settings\Eigenaar\Mijn documenten\Documenten van Valère\Mock06-07,10.PNG