Find out by the real roots of the denominator:
The singularities, corresponding to the points at infinity of C (u) , are find out by the real roots of the denominator
ω(u) = (1 - u)2 + 2u (1 - u) ω1 + u 2 = 0
They are given by

The curve reduces to
(i) a straight line if space w1 = 0
(ii) an elliptic segment if 0 < w1 <1
(iii) a parabolic segment if w1 = 1
(iv) a hyperbolic segment if w1 > 1
Geometrically, the curves are governed by the Parameter s = ω1/1 + ω1 as

The curve
passes through
(= P0 ) and
(= P2 ) along with the slope from

Therefore

, the tangents meets at
(= P )