What is focal Chord and If the chord joining P`(a(t_1)^2;2at_1)` and Q `(at_2^2;2at_2)` is the focal chord ; then `t_1t_2=-1`

If the line joining the points (at_1^2,2at_1)(at_2^2, 2at_2) is parallel to y=x then t_1+t_2=

If P(at_(1)^(2),2at_(1)) and Q(at_(2)^(2),2at_(2)) are the ends of focal chord of the parabola y^(2)=4ax then t_(1)t_(2)

Statement I The lines from the vertex to the two extremities of a focal chord of the parabola y^2=4ax are perpendicular to each other. Statement II If extremities of focal chord of a parabola are (at_1^2,2at_1) and (at_2^2,2at_2) , then t_1t_2=-1 .

The chord joining the points (x_(1),y_(1)) and (x_(2),y_(2)) on the curve y^(2)=12x is a focal chord if y_(1)y_(2)=

t 1 and  t 2 are two points on the parabola y^2 =4ax . If the focal chord joining them coincides with the normal chord, then  (a) t1(t1+t2)+2=0 (b) t1+t2=0 (c) t1*t2=-1 (d) none of these     

Tangents to the parabola y^2=4ax at P(at_1^2,2at_1)and Q(at_2^2,2at_2) meet at T. If DeltaPTQ is right - angled at T, then 1/(PS)+1/(QS) is equal to (where , S is the focus of the given parabola)

If (t^(2),2t) is one end ofa focal chord of the parabola,y^(2)=4x then the length of the focal chord will be: