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In the coordinate plane, a circle has center (2, -3) and [#permalink]
 16 Dec 2009, 04:20
Question Stats:
85% (01:53) correct
14% (01:07) wrong based on 12 sessions
In the coordinate plane, a circle has center (2, -3) and passes through the point (5, 0). What is the area of the circle? A. 3π B. 3√2π C. 3√3π D. 9π E. 18π
Last edited by Bunuel on 02 Apr 2012, 01:35, edited 1 time in total.
Edited the question and added the OA
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Re: Coordinate Geometry from Paper test [#permalink]
16 Dec 2009, 04:24
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IMO E ---> 18 pi r=sqrt[{5-2}^2+{0+3}^2]=3 sqrt2.......(dist formula) area=pi r^2 =pi* (3 sqrt2)^2=18 pi
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Re: Coordinate Geometry from Paper test [#permalink]
16 Dec 2009, 09:51
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E - 18pi
r^2 = [(5-2)^2 + (-3-0)^2] = 18. So Area = pi * r^2 = 18pi
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Re: Coordinate Geometry from Paper test [#permalink]
17 Dec 2009, 04:30
xcusemeplz2009 wrote: IMO E ---> 18 pi
r=sqrt[{5-2}^2+{0+3}^2]=3 sqrt2.......(dist formula)
area=pi r^2
=pi* (3 sqrt2)^2=18 pi hi can u elaborate what u mean by dis formula thanks
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Re: Coordinate Geometry from Paper test [#permalink]
17 Dec 2009, 04:55
OA is E
The distance formula in coordinate geometry is used to calculate the distance between 2 points whose coordinates are given
Lets say we have to calculate the distance between 2 points (x1, y1) and (x2, y2)
It is given by -
sqrt [ (x2-x1)^2 + (y2-y1)^2]
In this case since we are given the coordinates of the center and the fact that the circle passes thru (5,0), we can calculate the radius (needed for finding the area of the circle), by calculating the distance from the center to point (5,0)
Hope this helps
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Re: Coordinate Geometry from Paper test [#permalink]
09 Jan 2010, 23:52
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Got E. Used distance formula. Didn't solve for hypotenuse since it was an isoceles right triangle. Plugged in 3 sqrt 2 for radius in area formula. Thanks for the post. Got the answer pretty quickly. What level would you say this is?
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Re: Coordinate Geometry from Paper test [#permalink]
10 Jan 2010, 00:00
gottabwise wrote: Got E. Used distance formula. Didn't solve for hypotenuse since it was an isoceles right triangle. Plugged in 3 sqrt 2 for radius in area formula. Thanks for the post. Got the answer pretty quickly. What level would you say this is? Just copied problem into notes and recognized how I did extra work...should've just did distance formula b/w (5,0) and (2,-3)...r^2=(5-2)^3+(0--3)^2=sqrt18=3sqrt2. I guess that's why I'm reviewing right now.  Noticing that r^2 doesn't need to be solved for either.
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Re: Coordinate Geometry from Paper test [#permalink]
02 Apr 2012, 01:01
zaarathelab wrote: In the coordinate plane, a circle has center (2, -3) and passes through the point (5, 0). What is the area of the circle?
A. 3π
B. 3√2π
C. 3√3π
D. 9π
E. 18π Can any body draw the picture for this i thought y coordinate between (5,0) & (2,-3) will be radius i.e 3 and area will be 3*3pie
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Re: Coordinate Geometry from Paper test [#permalink]
02 Apr 2012, 01:34
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GMATD11 wrote: zaarathelab wrote: In the coordinate plane, a circle has center (2, -3) and passes through the point (5, 0). What is the area of the circle?
A. 3π
B. 3√2π
C. 3√3π
D. 9π
E. 18π Can any body draw the picture for this i thought y coordinate between (5,0) & (2,-3) will be radius i.e 3 and area will be 3*3pie The point is that the radius does not equal to 3, it equals to 3\sqrt{2}. You can find the length of the radius either with the distance formula (the formula to calculate the distance between two points (x_1,y_1) and (x_2,y_2) is d=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}) or with Pythagoras theorem. Look at the diagram below: Attachment: 
graph.png [ 10.12 KiB | Viewed 2358 times ]
The radius of the circle is the hypotenuse of a right isosceles triangle with the legs equal to 3: r^2=3^2+3^2=18 --> area=\pi{r^2}=18\pi. Answer: E. Hope it helps.
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Re: In the coordinate plane, a circle has center (2, -3) and [#permalink]
04 Apr 2012, 05:26
E
we get height as "3" using points (2,0) & (2,-3)
we get base as "3" using points (2,0) & (5,0)
therefore (radius)^2 = (3)^2 + (3)^2
radius = 3sqrt2
area = pi * r*r
=18pi
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Re: In the coordinate plane, a circle has center (2, -3) and
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04 Apr 2012, 05:26
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