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805+ (Hard)|   Geometry|      
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Bunuel
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Is arc ABC equal in length to arc DEF? (1) AD⊥CF (2) AD=CF 05 May 2021, 07:00
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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95% (hard)

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26% (01:23) correct 74% (01:15) wrong based on 117 sessions

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Is arc ABC equal in length to arc DEF?

(1) AD⊥CF
(2) AD=CF


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Is arc ABC equal in length to arc DEF? (1) AD⊥CF (2) AD=CF 08 May 2021, 01:00
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Bunuel

Is arc ABC equal in length to arc DEF?

(1) AD⊥CF
(2) AD=CF


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Consider two cases below:



Case 1: M is the center of the circle --> arc ABC = arc DEF;
Case 2: M is NOT the center of the circle --> arc ABC # arc DEF.
Not sufficient.

Answer: E.

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2.png
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TarunKumar1234
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Is arc ABC equal in length to arc DEF? (1) AD⊥CF (2) AD=CF Updated on: 12 May 2021, 12:39
Originally posted by TarunKumar1234 on 05 May 2021, 07:40.
Last edited by TarunKumar1234 on 12 May 2021, 12:39, edited 1 time in total.
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Is arc ABC equal in length to arc DEF?

Stat1: AD⊥CF
if AD and CF divide circle in 4 parts. So, arc ABC = arc DEF. But, if M is not the center then, arc ABC not equal to arc DEF Not Sufficient

Start2: AD=CF, dia are same in circle and doesn't help to get arc length. Not Sufficient

Combining both, Still we have a condition when M is not the center of the circle. Not Sufficient

So, It is E. :)
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Is arc ABC equal in length to arc DEF? (1) AD⊥CF (2) AD=CF 10 Aug 2021, 12:26
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Bunuel
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Is arc ABC equal in length to arc DEF?

(1) AD⊥CF
(2) AD=CF


Show Spoiler
Attachment:
1.jpg

Consider two cases below:



Case 1: M is the center of the circle --> arc ABC = arc DEF;
Case 2: M is NOT the center of the circle --> arc ABC # arc DEF.
Not sufficient.

Answer: E.

Show Spoiler
Attachment:
2.png
Show more

Hello Bunuel,
Thanks for the explanation.
Does an arc on the GMAT imply a circular arc?
If an arc does not imply a circular arc, and we have no other information telling us the figure is a circle, then the figure might not be a circle. It might as well be an ellipse or some other bounded region. Could we then choose option E without further analysis in the actual test and save some time?

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Is arc ABC equal in length to arc DEF? (1) AD⊥CF (2) AD=CF 29 Oct 2023, 14:03
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