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555-605 (Medium)|   Geometry|      
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What is the area of the circle above with center O? 20 Aug 2019, 02:28
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Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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25% (medium)

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76% (01:07) correct 24% (01:49) wrong based on 90 sessions

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What is the area of the circle above with center O?

(1) The area of triangle OAB is 50.

(2) The length of arc ACB is \(15\pi\).


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What is the area of the circle above with center O? 20 Aug 2019, 03:42
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Bunuel

What is the area of the circle above with center O?

(1) The area of OAB is 50.

(2) The length of arc ACB is \(15\pi\).


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#1
The area of OAB is 50
we have an isoscles ∆ so area ; x^2/2 = 50
x=10 ; area is 100pi
sufficient
#2
The length of arc ACB is \(15\pi\).
angle around c ; 270
so r ; 270/360 * 2*pi * r= 15 pi
solve for r = 10 sufficient
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What is the area of the circle above with center O? 20 Aug 2019, 03:56
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Hi Archit3110,

How did you calculate '270' as the angle around C?

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What is the area of the circle above with center O? 20 Aug 2019, 03:58
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himanshurajawat
Hi Archit3110,

How did you calculate '270' as the angle around C?

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see angle BOA= 90* and around center total 360 so angle for arc BCA ; 360-90 ; 270*
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What is the area of the circle above with center O? 20 Aug 2019, 05:53
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Bunuel

What is the area of the circle above with center O?

(1) The area of OAB is 50.

(2) The length of arc ACB is \(15\pi\).


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Asked: What is the area of the circle above with center O?

(1) The area of OAB is 50.
\(r^2/2 = 50\)
r = 10
\(Area = 100\pi\)
SUFFICIENT

(2) The length of arc ACB is \(15\pi\).
\(3/4C = 15\pi\) where C = circumference
\(C = 2\pi r = 20 \pi\)
r = 10
\(Area = 100\pi\)
SUFFICIENT

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What is the area of the circle above with center O? 08 Sep 2019, 19:13
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VeritasKarishma

What does statement 1 implies? Is it the area of the triangle or the area of the segment?
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What is the area of the circle above with center O? 09 Sep 2019, 02:02
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himanshurajawat
VeritasKarishma

What does statement 1 implies? Is it the area of the triangle or the area of the segment?
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It is odd that it is not mentioned whether OAB is the triangle or the sector. An official question would specify clearly. Here, I would just assume that it is the triangle because there is no mention of pi here.
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What is the area of the circle above with center O? 19 Sep 2019, 02:33
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VeritasKarishma
himanshurajawat
VeritasKarishma

What does statement 1 implies? Is it the area of the triangle or the area of the segment?

It is odd that it is not mentioned whether OAB is the triangle or the sector. An official question would specify clearly. Here, I would just assume that it is the triangle because there is no mention of pi here.
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Original question mentions triangle OAB, I copied incorrectly. Edited. Thank you!
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What is the area of the circle above with center O? 19 Sep 2019, 02:34
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Bunuel

What is the area of the circle above with center O?

(1) The area of triangle OAB is 50.

(2) The length of arc ACB is \(15\pi\).


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