In the rough sketch four concurrent lines are drawn in the Poincaré disk model and in the Euclidean model. If same angles $ (\alpha,\beta,\gamma,\delta) $ are enclosed at respective points of concurrency in either model then does the same trig definition of Cross Ratio hold good? [![enter image description here][1]][1] If that is so, and if the *same* three adjacent angles are given then is it correct to say they have the ***same Cross Ratio*** in euclidean and hyperbolic geometries? I need your help, appreciate your comments. [1]: https://i.sstatic.net/XB0u7.png