Difference between revisions of "University of South Carolina High School Math Contest/1993 Exam/Problem 27"

 
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== Problem ==
 
== Problem ==
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Suppose <math>\triangle ABC</math> is a triangle with area 24 and that there is a point <math>P</math> inside <math>\triangle ABC</math> which is distance 2 from each of the sides of <math>\triangle ABC</math>.  What is the perimeter of <math>\triangle ABC</math>?
  
<center><math> \mathrm{(A) \ } \qquad \mathrm{(B) \ } \qquad \mathrm{(C) \ } \qquad \mathrm{(D) \ } \qquad \mathrm{(E) \ }  </math></center>
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<center><math>  
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\mathrm{(A) \ } 12 \qquad \mathrm{(B) \ }24 \qquad \mathrm{(C) \ }36 \qquad \mathrm{(D) \ }12\sqrt{2} \qquad \mathrm{(E) \ }12\sqrt{3}  </math></center>
  
 
== Solution ==
 
== Solution ==
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Notice that <math>P</math> is the [[incenter]] of the [[triangle]]. The [[incircle]] has [[radius]] <math>2</math>. Thus, using <math>rs=A</math>, we have <math>2 \cdot s=24 \Longrightarrow s=12</math> and the perimeter is <math>24</math>.
  
 
== See also ==
 
== See also ==
 
* [[University of South Carolina High School Math Contest/1993 Exam]]
 
* [[University of South Carolina High School Math Contest/1993 Exam]]
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[[Category:Intermediate Geometry Problems]]

Revision as of 19:25, 22 July 2006

Problem

Suppose $\triangle ABC$ is a triangle with area 24 and that there is a point $P$ inside $\triangle ABC$ which is distance 2 from each of the sides of $\triangle ABC$. What is the perimeter of $\triangle ABC$?

$\mathrm{(A) \ } 12 \qquad \mathrm{(B) \ }24 \qquad \mathrm{(C) \ }36 \qquad \mathrm{(D) \ }12\sqrt{2} \qquad \mathrm{(E) \ }12\sqrt{3}$

Solution

Notice that $P$ is the incenter of the triangle. The incircle has radius $2$. Thus, using $rs=A$, we have $2 \cdot s=24 \Longrightarrow s=12$ and the perimeter is $24$.

See also