, 16) and Claim 1). ? Proof of (5.28). The geodesic triangle ABH has right angle at H. This together with Claim 2 and (5.26) implies the first asymptotic formula in (5.28): AH ? AB sin ?HAB ? bt n+1 . In the proof of the second formula in (5.28) we use the following claim, formula (5.26) and the fact that BP = O(t n?1 ) (follows from

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