GRE Big Book Test 7 Section 4 Q7

[Babayaga]

I am unable to solve the following problem on Triangles

[Leaderboard]

How to Ask Better GRE Questions on Forums

Since GregMat (who is a very chill person) doesn’t have any specific formatting rules when it comes to asking questions on the forums, I feel like there should at least be a reference text of some sort that can help people ask better questions and make the process more enjoyable for those who try to answer them. The Golden Rule: Imagine You’re Trying To Answer the Question Before you post your question about GRE preparation, practice questions, or strategies, try to put yourself in the shoes of…

[Babayaga]

I was unaware about the fact that big book questions were not allowed in this forum and will take this down.

[Leaderboard]

That isn’t the case - see the above link.

[ganesh]

To clarify, can you share with us more about your approach to the problem and what you don’t quite get?

[Babayaga]

Sure, i am able to arrive at the answer by assuming 2 things

1. ∆’s ADF & ABC are similar and ∆’s EFC and ABC are similar
2. ∆ ABC is equilateral

Then assigning numbers helps arrive at the answer, however, i am unable to justify my assumptions since :

1. There is only one angle common in the two sets of similar triangles listed above ( ∠A & ∠C respectively) and no mention of EC ∥ DF(for adf & abc) and EF ∥ AD(for efc & abc).
2. Unable to justify this assumption entirely.