The Product of the Inradius and Semiperimeter of a Triangle

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Let ABC be a triangle, its inradius, and
its semiperimeter. Then
.
Contributed by: Jay Warendorff (March 2011)
After work by: Alexander Bogomolny
Open content licensed under CC BY-NC-SA
Snapshots
Details
A. Bogomolny, "Relations between Various Elements of a Triangle," Interactive Mathematics Miscellany and Puzzles.
Permanent Citation
"The Product of the Inradius and Semiperimeter of a Triangle"
http://demonstrations.wolfram.com/TheProductOfTheInradiusAndSemiperimeterOfATriangle/
Wolfram Demonstrations Project
Published: March 7 2011