Bunuel wrote:
If BC = BD, what is the length of BC?Look at the diagram below:

As you can see fro the stem we can get that \(\angle{DBA} \angle{DAB}=2x\), from which it follows that AD = BD, thus AD = BD = BC.
(1) x = 30. This statement must be insufficient, because we are asked to find the length and all we know are angles. Not sufficient
(2) AD = 1 --> we know that AD = BC, thus BC = 1. Sufficient.
Answer: B.
Hope it's clear.
Totally follow the logic except one thing: AD = BD = BC. Why does this hold true? If 2x opposes the side that is length 1, shouldn't the length of the side that opposes x be 1/2? Given the way the question is set up, I can see that all sides necessarily must equal 1, but I just find it weird that this holds for different angles...
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