theorem :: JGRAPH_5:23

for sn being Real
for q being Point of (TOP-REAL 2) st - 1 < sn & sn < 1 & q `1 >= 0 & (q `2) / |.q.| < sn & |.q.| <> 0 holds
for p being Point of (TOP-REAL 2) st p = (sn -FanMorphE) . q holds
( p `1 >= 0 & p `2 < 0 )