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This is from GMATPrep. Point O is the center of the

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Manager
Joined: 14 Dec 2005
Posts: 74
This is from GMATPrep. Point O is the center of the [#permalink]

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06 Jan 2006, 17:35
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

This is from GMATPrep.

Point O is the center of the semicircle and point points B, C and D lie on the semicircle. If the length of line segment AB = OC, what is the degree measure of angle BAO?

(1) angle COD = 60 degrees
(2) angle BCO = 40 degrees

The answer is D. I don't see how you can get the answer wither either of those statements alone.
Director
Joined: 04 Oct 2005
Posts: 582
Location: Chicago

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07 Jan 2006, 15:37
Do you have a diagram for this...
I am not able to guess where A would lie?
Manager
Joined: 14 Dec 2005
Posts: 74

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07 Jan 2006, 21:08
Here u go..D is the end point on the right hand side
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geometry_210.jpg [ 7.34 KiB | Viewed 625 times ]

Director
Joined: 17 Dec 2005
Posts: 547
Location: Germany

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08 Jan 2006, 04:08
We know AB=OC

Thus AB=OC=OB

Therefore AO and BC are also equal, we can conclude triangle AOB is equal to BOC and these triangles are equilateral.

1) If COD=60 assume angle "x" is angle BOA

x+2x+60=180

x=40, since BOA=BAO BAO=40

2) BCO=40

BCO=BAO=40

Clearly D
08 Jan 2006, 04:08
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