Find the relation between t1 and t2 if normals at (at21,2at1) and (at22,2at2) meet on the parabola.
t1t2=2
Suppose that two lines have the equations
y=ax+c and y=bx+d
Hence, the point of intersection is
P(d−ca−b,ad−ca−b+c)=P(d−ca−b,ad−bca−b)
Here normal are y=−t1x+at31+2at1 and y=−t2x+at32+2at2
Therefore a=−t1,b=−t2,c=at31+2at1,d=at32+2at2
And x and y coordinate of P lie on y2=4ax which gives us on simplification t1t2=2