What is the equation of chord joining 2 points of a parabola given by parameters t1 and t2.
the parameters of the 2 joining points are t1 and t2
i.e.,A≡(at21,2at1)
B≡(at21,2at2)
∴ AB is given by
(y−2at1)=2a(t1−t2)a(t21−t22).(x−at21)
(y−2at1)=[2t1+t2](x−at21)
y(t1+t2)−2at21−2at1t2=2x−2at21
i.e.,2x−(t1+t2)y−2at1t2=0 is the required equation of the chord. This would be a useful formula is you could remember in higher level problems involving chord of a parabola.