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12 Mar 2012, 07:07
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
86% (00:56) correct
14%
(01:06)
wrong
based on 207
sessions
History
Date
Time
Result
Not Attempted Yet
Four points that form a polygon lie on the circumference of the circle. What is the area of the polygon ABCD
(1) The radius of the circle is \(\frac{\sqrt{2}}{2}\)
(2) ABCD is square.
The figure is drawn in such a way that the two angles are shown to be right angles.
Kaplan book says both statements are required to solve, but i think that state 1 alone is sufficient.
Given that we know the angle is a right angle and that a diagonal AC is joined as well. We can say that AC is a diameter (angle inscribed in a semi circle). And if we join point D with say centre O, OA OD And OC will be equal. We already know the radius. OD will be perpendicular to the base (diameter AC) and hence we can get the area. We dont need to know whether ABCD is square or not.
Could someone shed some light ?
Edit: Apologies for amateur fine art skills
Thanks
(1) The radius of the circle is \(\frac{\sqrt{2}}{2}\)
(2) ABCD is square.
The figure is drawn in such a way that the two angles are shown to be right angles.
Kaplan book says both statements are required to solve, but i think that state 1 alone is sufficient.
Given that we know the angle is a right angle and that a diagonal AC is joined as well. We can say that AC is a diameter (angle inscribed in a semi circle). And if we join point D with say centre O, OA OD And OC will be equal. We already know the radius. OD will be perpendicular to the base (diameter AC) and hence we can get the area. We dont need to know whether ABCD is square or not.
Could someone shed some light ?
Edit: Apologies for amateur fine art skills
Thanks
Attachments
Untitled.png [ 3.68 KiB | Viewed 6671 times ]
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
12 Mar 2012, 09:26
Kudos
Bookmarks
mist3rh
The red part is not correct.
Four points that form a polygon lie on the circumference of the circle. What is the area of the polygon ABCD
(1) The radius of the circle is \(\frac{\sqrt{2}}{2}\) --> consider two quadrialaterals below:
Attachment:
Inscibed polygon.png [ 40.54 KiB | Viewed 6622 times ]
(2) ABCD is square. We know nothing about the measurements of either the square or the circle. Not sufficient.
(1)+(2) We know the radius of a circle and that ABCD is a square, which is sufficient to find the area.
Answer: C.
Hope it's clear.
12 Mar 2012, 10:56
Kudos
Bookmarks
Thanks mate ! The problem shows the diagram in a way that reflects that point D joined with centre O would be perpendicular (given that diagrams are drawn to scale unless specified). But obviously thats not the case. The diagram positioning was primarily why i assumed OD would be perpendicular. I hope GMAT does not have such ambiguities.
