for cn being Real
for K1 being non empty Subset of (TOP-REAL 2)
for f being Function of ((TOP-REAL 2) | K1),R^1 st cn < 1 & ( for p being Point of (TOP-REAL 2) st p in the carrier of ((TOP-REAL 2) | K1) holds
f . p = |.p.| * (- (sqrt (1 - (((((p `1) / |.p.|) - cn) / (1 - cn)) ^2)))) ) & ( for q being Point of (TOP-REAL 2) st q in the carrier of ((TOP-REAL 2) | K1) holds
( q `2 <= 0 & (q `1) / |.q.| >= cn & q <> 0. (TOP-REAL 2) ) ) holds
f is continuous