Pre rmo 2012

Geometry Level 2

A triangle with perimeter 7 has integer side lengths.What is the maximum possible area of such a triangle?

The answer is of the form a b c \frac{a\sqrt{b}}{c} .Enter your answer as the sum of a a , b b and c c .


The answer is 14.

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2 solutions

Subhiksha Nd
Sep 5, 2015

SIMPLE! Since its perimeter is 7, and the lengths of sides are integers, imagine the number of triads whose sum equals 7. Since its a triangle, the sum of any two sides should be greater than the third side and their difference should be less than the third side.

THis leaves us with the triad ( 2,3,2) Using Heron's formula, s=3.5, Therefore, Area= 3(root 7)/4

a=3, b=7, c=4 a+b+c= 14

Thus, 14 is the answer!

Ramiel To-ong
Sep 26, 2015

nice problem

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