Proof of formula for Base,Altitude,Leg of an Isosceles Tr. : GMAT Quantitative Section
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# Proof of formula for Base,Altitude,Leg of an Isosceles Tr.

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Intern
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Proof of formula for Base,Altitude,Leg of an Isosceles Tr. [#permalink]

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13 Oct 2013, 03:14
Guys,

Please some one explain how the base, leg , altitude formula arrived for isosceles triangle which is given in GMAT Club math book.

Anuj
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Joined: 19 Apr 2013
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Concentration: Entrepreneurship, Finance
GMAT Date: 06-05-2015
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Re: Proof of formula for Base,Altitude,Leg of an Isosceles Tr. [#permalink]

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23 Oct 2013, 10:12
anu1706 wrote:
Guys,

Please some one explain how the base, leg , altitude formula arrived for isosceles triangle which is given in GMAT Club math book.

Anuj

These can be easily proved with the help of Pythagaourus theorem.

Consider the triangle ABC in which BC is base and A is vertex.Consider AB and AC are equal side.
So when ever you draw a altitude from vertex A to Base BC it will meet it at D, and D will be the midpoint of BC.

So you find Altitude by :: AB^2=Alti^2+(BC/2)^2
AB=\sqrt{Alti^2+(BC/2)^2}
Alti = \sqrt{AB^2 - (BC/2)^2}
(BC/2)^2=AB^2-Alti^2

BC=2\sqrt{(AB^2-Alti^2)}

So it proves how the results are obtained.

+1 Kudos if you like.

_________________

Thanks,
AB

+1 Kudos if you like and understand.

Re: Proof of formula for Base,Altitude,Leg of an Isosceles Tr.   [#permalink] 23 Oct 2013, 10:12
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