DS KAPLAN GEOMETRY

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DS KAPLAN GEOMETRY

by ddo » Wed Oct 15, 2008 12:46 pm
In the figure above,does A=B?

1- x=y
2- c=X

I quite did not understand the explanation.
Note that although shown parallel, we do not know if the lines are parallel or not.
I thought if c=x then A<>B as B=180-C and A=X=C, but does not seem to be OK. Any thoughts?
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by msd_2008 » Wed Oct 15, 2008 5:33 pm
Is the OA B?

Statement 1 says that x=y. Therefore x=y=90 degrees. But this does not give us any information about the lines being parallel or not and so we cannot comment on whether a=b or not. Hence insufficient.

Statement 2 says c=x. But we know that x=A because they are opposite angles. Hence a=c and this means that both a & c are 90 degree angles. Therefore the lines have to be parallel to each other. Hence a=b because they are corresponding angles of parallel lines. Thus statement 2 is sufficient to answer the question.
Hence B.
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by mental » Fri Oct 17, 2008 6:23 am
What is the OA?
is it C?

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by ddo » Sun Oct 19, 2008 2:49 am
Answer is C, why?

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by tkhalid » Sun Oct 19, 2008 4:02 am
i think answer is C.

Reason: if x=90=y, does not tell anything but tells of a supplementary angle.
so (i) is insufficient. and if c=x=90, then definitely A=B=90. So both 1 and 2 are required to solve the problem.

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by stubbornp » Sun Oct 19, 2008 7:30 am
Answer should be C..