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555-605 (Medium)|   Geometry|      
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Bunuel
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In triangle ABC above, what is the measure of angle DBC ? 24 Dec 2017, 01:54
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B
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35% (medium)

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69% (01:50) correct 31% (01:52) wrong based on 118 sessions

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In triangle ABC above, what is the measure of angle DBC ?

(1) Triangle ABD is isosceles.
(2) Angle ADB = 100
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B
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In triangle ABC above, what is the measure of angle DBC ? 24 Dec 2017, 01:54
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Bunuel


In triangle ABC above, what is the measure of angle DBC ?

(1) Triangle ABD is isosceles.
(2) Angle ADB = 100
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Similar question from OG: https://gmatclub.com/forum/in-triangle- ... 68281.html
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In triangle ABC above, what is the measure of angle DBC ? Updated on: 24 Dec 2017, 05:42
Originally posted by Mick1005 on 24 Dec 2017, 04:07.
Last edited by Mick1005 on 24 Dec 2017, 05:42, edited 1 time in total.
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IMO :B
statement1: Dont know what angle is equal to what.insuff
Statement2: <ADB=100
=> <ADB + 2x=180 (Linear Pair)
=> x=40.
=><DBC=180-80-80=20. Sufficient.

Waiting for OA
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In triangle ABC above, what is the measure of angle DBC ? 24 Dec 2017, 05:20
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Bunuel


In triangle ABC above, what is the measure of angle DBC ?

(1) Triangle ABD is isosceles.
(2) Angle ADB = 100
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IMO answer should be "B". Awaiting OA

Statement 1: Even without knowing the fact given in statement 1, we can conclude that ABD=x. Thus this point is insufficient

Statement 2: 100=2x + DBC; also DBC=180-4x
=>2x=80 =>x=40; therefore, DBC=20. This is sufficient
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In triangle ABC above, what is the measure of angle DBC ? Updated on: 25 Dec 2017, 12:12
Originally posted by exc4libur on 24 Dec 2017, 14:03.
Last edited by exc4libur on 25 Dec 2017, 12:12, edited 1 time in total.
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Bunuel
Bunuel


In triangle ABC above, what is the measure of angle DBC ?

(1) Triangle ABD is isosceles.
(2) Angle ADB = 100

Similar question from OG: https://gmatclub.com/forum/in-triangle- ... 68281.html
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The interior angles of a triangle sum to 180.
An isosceles triangle has 2 equal angles that are equal sides.
Since \(DBC = 180 - (2x+2x)\), all we need to do is find the value for \(x\).

(1) Triangle ABD is isosceles. So, AB = BD or AB = AD, since we don't know which one we cannot find DBC, this is insufficient.

(2) Angle ADB = 100. Angles ADB + BDC = 180, so 100 + 2x = 180, 2x = 180 - 100, x = 40. To find DBC, this is sufficient.

(B) is the answer.
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In triangle ABC above, what is the measure of angle DBC ? 25 Dec 2017, 03:39
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IMO : B
(1) We don't know whether AB = BD or AB = AD
(2) We certainly know AB = BD => ADB = 100 = DBC + DCB = 180 - 2.2x + 2x => We can calculate x hence we will know DBC angle
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In triangle ABC above, what is the measure of angle DBC ? 23 Feb 2023, 10:57
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