I don't know what I am supposed to do. Please, help
Problem: Similarity of noncongruent triangles is not possible in hyperbolic geometry. Where is the Euclidean parallel assumption used in the proof of the basic proportionality theorem?
There are 2 parts, one is about hyperbolic geometry and other is about Euclidean parallel.
In hyperbolic, Euclidean parallel is not applied. Hence I don't see relation between 2 parts on the problem. Appreciate any tips.

Question

I don't know what I am supposed to do. Please, help
Problem: Similarity of noncongruent triangles is not possible in hyperbolic geometry. Where is the Euclidean parallel assumption used in the proof of the basic proportionality theorem? 
There are 2 parts, one is about hyperbolic geometry and other is about Euclidean parallel.
In hyperbolic, Euclidean parallel is not applied. Hence I don't see relation between 2 parts on the problem. Appreciate any tips.