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The lengths of two sides of isosceles triangle XYZ are 8 and 18. [#permalink]
GreenlightTestPrep wrote:
The lengths of two sides of isosceles triangle XYZ are 8 and 18.


Quantity A
Quantity B
The perimeter of triangle XYZ
36



Key property : If two sides of a triangle have lengths A and B, then . . .
the DIFFERENCE between A and B < length of third side < the SUM of A and B

Since an isosceles triangle has two the sides of equal length, there are two possible cases to consider:
case i: The three sides have lengths 8, 18 and 18
case ii: The three sides have lengths 8, 8 and 18

Important: case ii breaks the above property.
If we let the side with length 18 be the third side, we get: 8 - 8 < 18 < 8 + 8
Simplify to get: 0 < 18 < 16, which is not true.
So, case ii is impossible

Case i meets the above property, so the sides must have lengths 8, 18 and 18, which means the perimeter = 8 + 18 + 18 = 44

Answer: A
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Re: The lengths of two sides of isosceles triangle XYZ are 8 and 18. [#permalink]
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Re: The lengths of two sides of isosceles triangle XYZ are 8 and 18. [#permalink]
Mishra04 wrote:
D

The correct answer is A. See the explanations above.
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Re: The lengths of two sides of isosceles triangle XYZ are 8 and 18. [#permalink]
1
We need to be very careful. In every Question, Test maker try to fool test taker. Here is the same case. Most of test taker in rush forget to check whether their is possibility of having third side 8 or not, eventually, tend to make mistake. Likewise, in another scenario, they started to stating QUESTION like figure are not drawn to scale just to make us tempting :lol
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Re: The lengths of two sides of isosceles triangle XYZ are 8 and 18. [#permalink]
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Re: The lengths of two sides of isosceles triangle XYZ are 8 and 18. [#permalink]
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