Correct answer is (a) In a parabola vertex is the mid point of focus and foot of directrix.Correct answer is (b) P(at12,2at1)&Q(at22,2at2) are two points on y2=4ax such that t1t2=−1, then normals at P and Q are perpendicular.
Correct answer is (c) There doesn't exist any tangent of y2=4ax which is parallel to x-axis.