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Sub 505 (Easy)|   Geometry|      
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TheUltimateWinner
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The average length of the sides of triangle ABC is 12. What is the per Updated on: 29 Sep 2016, 03:44
Originally posted by TheUltimateWinner on 28 Sep 2016, 12:58.
Last edited by Bunuel on 29 Sep 2016, 03:44, edited 1 time in total.
Renamed the topic and edited the question.
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The average length of the sides of triangle ABC is 12. What is the perimeter of triangle ABC?
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22.PNG
22.PNG [ 14.69 KiB | Viewed 6576 times ]

This question did not use the word 'approximately'.
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E
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TheUltimateWinner
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The average length of the sides of triangle ABC is 12. What is the per 28 Sep 2016, 13:01
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My answer option says it is 36.01, which is not found in the answer options. Should not the writer of this book use the word 'approximately'?
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Bunuel
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The average length of the sides of triangle ABC is 12. What is the per 29 Sep 2016, 03:47
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iMyself
The average length of the sides of triangle ABC is 12. What is the perimeter of triangle ABC?
Attachment:
22.PNG

This question did not use the word 'approximately'.
Show more

(average) = (perimeter)/3;

12 = (perimeter)/3;

(perimeter) = 36.

Answer: E.

P.S. Why should they mention "approximately"?
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The average length of the sides of triangle ABC is 12. What is the per 29 Sep 2016, 04:10
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Bunuel
iMyself
The average length of the sides of triangle ABC is 12. What is the perimeter of triangle ABC?
Attachment:
22.PNG

This question did not use the word 'approximately'.

(average) = (perimeter)/3;

12 = (perimeter)/3;

(perimeter) = 36.

Answer: E.

P.S. Why should they mention "approximately"?
Show more

The correct answer is 36 according to this books.
here, (S+S root 3+2S)/3=12
------> S=7.61
So, S+S root 3+2S=36.01, which is not exactly 36.
did I make any mistake by saying 36 and 36.01 are not the same thing, here?
Should not the writer use the word 'approximately'?
The measurement of this angle is 30-60-90, right? but, if the perimeter is 36, i can say the measurement is not correct; the measurement may be 29-60-90. But, in the figure of this question, it is already said that the two angles is 60 and 90. so, the rest of the angle must be 30, isn't it? if the rest of the angle is 30, then the perimeter must be 36.01, not exactly 36.
Thanks Bunuel for your help.
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The average length of the sides of triangle ABC is 12. What is the per 29 Sep 2016, 04:21
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iMyself
Bunuel
iMyself
The average length of the sides of triangle ABC is 12. What is the perimeter of triangle ABC?
Attachment:
22.PNG

This question did not use the word 'approximately'.

(average) = (perimeter)/3;

12 = (perimeter)/3;

(perimeter) = 36.

Answer: E.

P.S. Why should they mention "approximately"?

The correct answer is 36 according to this books.
here, (S+S root 3+2S)/3=12
------> S=7.61
So, S+S root 3+2S=36.01, which is not exactly 36.
did I make any mistake by saying 36 and 36.01 are not the same thing, here?
Should not the writer use the word 'approximately'?
The measurement of this angle is 30-60-90, right? but, if the perimeter is 36, i can say the measurement is not correct; the measurement may be 29-60-90. But, in the figure of this question, it is already said that the two angles is 60 and 90. so, the rest of the angle must be 30, isn't it? if the rest of the angle is 30, then the perimeter must be 36.01, not exactly 36.
Thanks Bunuel for your help.
Show more

The point is that S is NOT exactly 7.61 there. It's \(6(3- \sqrt 3)\) and if you substitute this value you'l get exactly 36.

Hope it's clear.
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Bunuel
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The average length of the sides of triangle ABC is 12. What is the per 29 Sep 2016, 04:23
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Bunuel
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Bunuel

(average) = (perimeter)/3;

12 = (perimeter)/3;

(perimeter) = 36.

Answer: E.

P.S. Why should they mention "approximately"?

The correct answer is 36 according to this books.
here, (S+S root 3+2S)/3=12
------> S=7.61
So, S+S root 3+2S=36.01, which is not exactly 36.
did I make any mistake by saying 36 and 36.01 are not the same thing, here?
Should not the writer use the word 'approximately'?
The measurement of this angle is 30-60-90, right? but, if the perimeter is 36, i can say the measurement is not correct; the measurement may be 29-60-90. But, in the figure of this question, it is already said that the two angles is 60 and 90. so, the rest of the angle must be 30, isn't it? if the rest of the angle is 30, then the perimeter must be 36.01, not exactly 36.
Thanks Bunuel for your help.

The point is that S is NOT exactly 7.61 there. It's \(6(3- \sqrt 3)\) and if you substitute this value you'l get exactly 36.

Hope it's clear.
Show more

Having said that, the method I used is MUCH easier and shorter.
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The average length of the sides of triangle ABC is 12. What is the per 29 Sep 2016, 05:25
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Bunuel
Bunuel
iMyself


The correct answer is 36 according to this books.
here, (S+S root 3+2S)/3=12
------> S=7.61
So, S+S root 3+2S=36.01, which is not exactly 36.
did I make any mistake by saying 36 and 36.01 are not the same thing, here?
Should not the writer use the word 'approximately'?
The measurement of this angle is 30-60-90, right? but, if the perimeter is 36, i can say the measurement is not correct; the measurement may be 29-60-90. But, in the figure of this question, it is already said that the two angles is 60 and 90. so, the rest of the angle must be 30, isn't it? if the rest of the angle is 30, then the perimeter must be 36.01, not exactly 36.
Thanks Bunuel for your help.

The point is that S is NOT exactly 7.61 there. It's \(6(3- \sqrt 3)\) and if you substitute this value you'l get exactly 36.

Hope it's clear.

Having said that, the method I used is MUCH easier and shorter.
Show more
I get it Bunuel. Thank you so much.
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The average length of the sides of triangle ABC is 12. What is the per 27 Feb 2017, 05:18
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Let the sides be a,b,c.
The average of length = (a + b+ c)/3 = 12
Therefore perimeter = a + b+ c = 12*3 =36
Option E
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