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In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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09 Apr 2015, 06:23
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In the diagram above, AC = AB, and angle DAB = angle DBC. What is the measure of angle BCD? (1) angle BDC = 2*(angle DAB) (2) AD = BD Kudos for a correct solution.Attachment:
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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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09 Apr 2015, 08:48
Bunuel wrote: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the measure of angle BCD? (1) angle BDC = 2*(angle DAB) (2) AD = BD Kudos for a correct solution.Attachment: The attachment gdrtq_img4.png is no longer available Answer D .
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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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09 Apr 2015, 09:29
Naina1 wrote: I'll go with C.
Given : AC=AB this implies angle ABC=angle ACB Let angle DAB=x=angle DBC
Condition 1: angle BDC=2*angle DAB=2x So, angle BCD=180(x+2x)=1803x This could not help any further.
Condition 2: AD=BD This gives angle DAB=angle DBA=x This also is insufficient.
Both 1+2 As angle ABC=angle ACB angle DBA+angle DBC=angle ACB x+x=1803x 2x=1803x 5x=180 x=36 So, angle BCD=1803x=1803*36=180108=72 please see attached for option A. you can do the same for option B.
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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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09 Apr 2015, 09:09
I'll go with C.
Given : AC=AB this implies angle ABC=angle ACB Let angle DAB=x=angle DBC
Condition 1: angle BDC=2*angle DAB=2x So, angle BCD=180(x+2x)=1803x This could not help any further.
Condition 2: AD=BD This gives angle DAB=angle DBA=x This also is insufficient.
Both 1+2 As angle ABC=angle ACB angle DBA+angle DBC=angle ACB x+x=1803x 2x=1803x 5x=180 x=36 So, angle BCD=1803x=1803*36=180108=72



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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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09 Apr 2015, 09:34
my bad.. yes each statement alone is sufficient.



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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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13 Apr 2015, 04:06
Bunuel wrote: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the measure of angle BCD? (1) angle BDC = 2*(angle DAB) (2) AD = BD Kudos for a correct solution.Attachment: gdrtq_img4.png VERITAS PREP OFFICIAL SOLUTION:From the prompt, we know that triangle ABC is isosceles, with AB = AC and angle ABC = angle DCB. Because angle DAB = angle DBC, and they share the angle at C, we know triangle BCD is similar to triangle ABC; therefore, triangle BCD must also be isosceles, with BC = BD and angle BDC = angle BCD. For simplicity, let’s say that x = angle DAB = angle DBC y = angle ABC = angle DCB = angle BDC We know that (x + 2y) = 180°, and the prompt is asking for the value of y. Statement #1: angle BDC = 2*(angle DAB) In other words, y = 2x. Then x + 2y = x + 4x = 5x = 180° This means x = 36° and y = 72°. This statement leads directly to the numerical value sought in the prompt. This statement, alone and by itself, is sufficient. Statement #2: AD = BD This tell us that triangle ABD is also isosceles. This means that angle DAB = angle ABD. Think about angle ABD. That angle is the “leftover” between two angles we have already discussed: angle ABD = (angle ABC) – (angle CBD) = y – x Well, angle DAB = x, so if these two are equal, this means: y – x = x y = 2x This turns out to be the exact same information that was given in statement #1, which we already know is full sufficient. Answer = (D) (BTW, more than you need to know for the GMAT, but these are Golden Triangles, because the ratio AB/BC equals the Golden Ratio! )
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In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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13 Apr 2015, 15:52
Attachment:
isosceles triangle.JPG [ 16.07 KiB  Viewed 47022 times ]
In the diagram above, AC = AB, and angle DAB = angle DBC. What is the measure of angle BCD? Statement #1: angle BDC = 2*(angle DAB) Statement #2: AD = BD For a collection of 12 challenging DS practice questions, and the OE for this particular question, see: http://magoosh.com/gmat/2015/gmatdata ... uestion2/Mike
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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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14 Apr 2015, 02:21
given \(\triangle ABC\) is an isosceles triangle \(AB = AC\) \(\angle ABC = \angle ACB\) \(= ?\) Let's assume \(\angle ABC = \angle ACB = x; \angle CAB = \angle DBC = y\)
from the question stem: \(2x + y = 180\) > (i)
Statement 1: \(\angle BDC = 2*\angle DAB = 2*\angle DBC\) From \(\triangle DBC x + 3y = 180\)  (ii) Solving (i) and (ii) \(x = 72; y = 36; \angle ACB = 72\) Sufficient
Statement 2: AD = BD, \(\triangle ABD is isosceles, \angle ABD = \angle DAB =y\) So \(\angle ABC = 2y\) \(x + 3y = 180\) > (iii); same as (ii) Solving (i) and (iii) \(x = 72; y = 36; \angle ACB = 72\) Sufficient
Answer D



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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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09 Sep 2016, 06:15
Bunuel wrote: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the measure of angle BCD? (1) angle BDC = 2*(angle DAB) (2) AD = BD Kudos for a correct solution.Attachment: The attachment gdrtq_img4.png is no longer available Attachment:
Capture.JPG [ 31.76 KiB  Viewed 45657 times ]
St 1: BDC = 2 (180 2x) Sum of angles in triangle BDC = 180. On solving we get x =72 St 2: AD+BD .. angles opp to equal sides are equal. 1802x= 3x180 x=72



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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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07 Aug 2019, 19:40
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Re: In the diagram above, AC = AB, and angle DAB = angle DBC. What is the
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