Difference between revisions of "1967 AHSME Problems/Problem 5"

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== Solution ==
 
== Solution ==
<math>\fbox{D}</math>
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The area <math>K</math> of the triangle can be expressed in terms of its inradius <math>r</math> and its semiperimeter <math>s</math> as:
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<cmath> K = r \times s = r \times \frac{P}{2}</cmath>
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So, <math>\frac{P}{K} = \boxed{\textbf{(C) } \frac{2}{r}}</math>.
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~ proloto
  
 
== See also ==
 
== See also ==
{{AHSME box|year=1967|num-b=4|num-a=6}}   
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{{AHSME 40p box|year=1967|num-b=4|num-a=6}}   
  
 
[[Category:Introductory Algebra Problems]]
 
[[Category:Introductory Algebra Problems]]
 
{{MAA Notice}}
 
{{MAA Notice}}

Latest revision as of 19:33, 28 September 2023

Problem

A triangle is circumscribed about a circle of radius $r$ inches. If the perimeter of the triangle is $P$ inches and the area is $K$ square inches, then $\frac{P}{K}$ is:

$\text{(A)}\text{ independent of the value of} \; r\qquad\text{(B)}\ \frac{\sqrt{2}}{r}\qquad\text{(C)}\ \frac{2}{\sqrt{r}}\qquad\text{(D)}\ \frac{2}{r}\qquad\text{(E)}\ \frac{r}{2}$


Solution

The area $K$ of the triangle can be expressed in terms of its inradius $r$ and its semiperimeter $s$ as: \[K = r \times s = r \times \frac{P}{2}\]

So, $\frac{P}{K} = \boxed{\textbf{(C) } \frac{2}{r}}$.

~ proloto

See also

1967 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 4
Followed by
Problem 6
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All AHSME Problems and Solutions

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