advice needed

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advice needed

by likewhoa » Sun Nov 18, 2007 7:47 am
Is the measure of one of the interior angles is quadrilateral ABCD equal to 60 degrees?

(1) 2 of the interior angles of ABCD are right angles
(2) The degree measure of angle ABC is twice the degree measure of angle BCD.


answer E


I'm confused since my initial answer was C...
can anyone explain how to solve this one?
Source: — Data Sufficiency |

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by ri2007 » Sun Nov 18, 2007 7:57 am
Start with what you know

First sum of interior angles is quadrilateral = 360

now combined you know 2 angles are 90 and one angle is twice the other.

So it is possible that the angles are - 90-90- 60-120 0r 90-90-45-115. both combinations satisfy all conditions but in one angle is = 60 and in the other it is not.