AlgCalcOne: Tangents to Parametric Curves
- Author:
- Paul Miller
How can we cancel the the factor (t - u) in the product of points AB for
A = [t : :t²: 1] , B = [u : u² : 1] giving the 'line' ( (t - u)(t + u) : (u - t) : (u - t)tu )
and then set u = t?
One possible answer is that the u and t are only made equal projectively so can actually define a plane formed of parallel ( but not coincident ) lines
We use the projective form of parabola: z = x² / y