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# In the diagram above, O is the center of the circle

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Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4488

Kudos [?]: 8753 [1], given: 105

In the diagram above, O is the center of the circle [#permalink]

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01 May 2013, 10:40
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In the diagram above, O is the center of the circle, DC = a and DO = b. What is the area of the circle?

Statement #1: $$a^2 - 2ab + b^2 = 36$$

Statement #2: a + b = 22

For a discussion of the important algebra formulas involved, as well as a full solution to this particular problem, see:
http://magoosh.com/gmat/2013/three-alge ... -the-gmat/
[Reveal] Spoiler: OA

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Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Kudos [?]: 8753 [1], given: 105

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Manager
Joined: 26 Feb 2013
Posts: 53

Kudos [?]: 15 [0], given: 16

Concentration: Strategy, General Management
GMAT 1: 660 Q50 V30
WE: Consulting (Telecommunications)
Re: In the diagram above, O is the center of the circle [#permalink]

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01 May 2013, 11:13
Option A.

DC= a and DO =b
OC= DC-DO = b-a = radius of the circle.

From stmt 1:
(b-a)^2=36 or (b-a)=6 and area = 36pi. sufficient

From stmt 2:

we know a+b but we need to know the value of b-a. hence this is insufficient.

Kudos [?]: 15 [0], given: 16

Non-Human User
Joined: 09 Sep 2013
Posts: 15617

Kudos [?]: 283 [0], given: 0

Re: In the diagram above, O is the center of the circle [#permalink]

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19 May 2016, 01:00
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Kudos [?]: 283 [0], given: 0

Manager
Joined: 13 Dec 2013
Posts: 172

Kudos [?]: 28 [0], given: 122

Location: United States (NY)
GMAT 1: 710 Q46 V41
GMAT 2: 720 Q48 V40
GPA: 4
WE: Consulting (Consulting)
Re: In the diagram above, O is the center of the circle [#permalink]

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15 Apr 2017, 17:29
Option A.

DC= a and DO =b
OC= DC-DO = b-a = radius of the circle.

From stmt 1:
(b-a)^2=36 or (b-a)=6 and area = 36pi. sufficient

From stmt 2:

we know a+b but we need to know the value of b-a. hence this is insufficient.

I believe it's (a-b) we're looking for here.

(a-b)(a-b)=r^2=36 So, area is 36pi

Kudos [?]: 28 [0], given: 122

Re: In the diagram above, O is the center of the circle   [#permalink] 15 Apr 2017, 17:29
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