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In the figure above, D is a point on side AC of ABC. Is ABC [#permalink]
 22 Mar 2008, 01:59
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18. In the figure above, D is a point on side AC of ΔABC. Is ΔABC is isosceles? (1) The area of triangular region ABD is equal to the area of triangular region DBC. (2) BD┴AC and AD = DC
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triang ABCD.JPG [ 3.38 KiB | Viewed 477 times ]
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Jimmy Low, Frankfurt, Germany
Blog: http://mytrainmaster.wordpress.com
GMAT Malaysia: http://gmatmalaysia.blogspot.com
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Re: 1000DS: Section 2 Question 18 [#permalink]
22 Mar 2008, 07:02
Statement 1:
Tells us that Area of ABD is same as area of DBC. It might happen that AD is very small and DC is large thereby making AB longer and BC shorter. The reverse can also happen. As such this statement on its own in not sufficient.
Statement 2:
Tells us that AD = DC and BC is perpendicular on AC. This is good enough to tell us that AB = BC. You can also use triangle property to prove that AB = BC. (Two sides of triangles compared are equal).
Answer B.
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Re: 1000DS: Section 2 Question 18 [#permalink]
22 Mar 2008, 08:15
Yes, OA = B. Do not quite understand your explanation for Statement 1. Mind elaborate?
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Jimmy Low, Frankfurt, Germany
Blog: http://mytrainmaster.wordpress.com
GMAT Malaysia: http://gmatmalaysia.blogspot.com
Last edited by jimmylow on 22 Mar 2008, 08:16, edited 1 time in total.
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Manager
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Re: 1000DS: Section 2 Question 18 [#permalink]
22 Mar 2008, 08:15
Yes, OA = B. Do not quite understand your explanation for Statement 1. Mind elaborate?
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Jimmy Low, Frankfurt, Germany
Blog: http://mytrainmaster.wordpress.com
GMAT Malaysia: http://gmatmalaysia.blogspot.com
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Re: 1000DS: Section 2 Question 18 [#permalink]
22 Mar 2008, 09:19
ADB and BDC can have same area although AB and BC can be different. They do not have to be of same length. Height of both triangle is same. That means AD = DC. However as BD is can be at any angle rather than being perpendicular to AC, so value of AB and BC will vary and can be equal and cannot be equal. So this statement alone is not sufficient.
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Re: 1000DS: Section 2 Question 18
[#permalink]
22 Mar 2008, 09:19
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