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Prove that the Perimeter of a Triangle is Greater than the Sum of Its Three Medians. - Mathematics

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Question

Prove that the perimeter of a triangle is greater than the sum of its three medians.

Sum

Solution

Given: A ΔABC ion which AD, BE and CF are its medians.
To Prove: we know that the sum of any two dies of a triangle is greater than twice the median bisecting the third side. Therefore,
AD is the median bisecting BC
⇒ AB + AC > 2AD                    ...(i)
BE is the median bisecting AC ...(ii)
And, CF is the median bisecting AB

⇒ BC + AC > 2EF                      ...(iii)
Adding (i), (ii) and (iii), we get
(AB + AC) + (AB + BC) + (BC + AC) > 2. AD + 2. BE + 2. BE + 2. CF
⇒ 2 (AB + BC + AC) > 2 (AD + BE + CF)
⇒ AB + BC + AC > AD + BE + CF.

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Chapter 13: Inequalities in Triangles - Exercise 13.1

APPEARS IN

Frank Mathematics [English] Class 9 ICSE
Chapter 13 Inequalities in Triangles
Exercise 13.1 | Q 7
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