DS KAPLAN GEOMETRY

[ddo]

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?

[msd_2008]

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.

[mental]

What is the OA?
is it C?

[ddo]

Answer is C, why?

[tkhalid]

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.

[stubbornp]

Answer should be C..