Let P(at12,2at1) and Q(at22,at2) be a focal chord of the parabola y2=4ax. The tangents at P and Q intersect at (at1t2,a(t1+t2)) ∴x1=at1t2 and y1=a(t1+t2) ⇒x1=−a and y1=a(t1+t2)[∵PQ is a focal chord ⇒t1t2=−1] The normals at P and Q intersect at [2a+a(t12+t22+t1t2),−at1t2(t1+t2)] ∴x2=2a+a(t12+t22+t1t2) and y2=−at1t2(t1+t2) ⇒x2=a+a(t12+t22) and y2=a(t1+t2) ∴y1=y2