[" 18.If the tangents and normals at the extremities of a focal chord of a parabola intersect at "(x_(1),y_(1))" and "],[(x_(2),y_(2))" respectively,then : "],[[" (A) "x_(1)=x_(2)," (B) "x_(1)=y_(2)],[" 19.Locus of the intersection of the tangents at the ends of the nomal chords of the parabola "y^(2)=4ax" s: "]],[[" 19.Locus of the intersection of the tangents at the ends of the nomal chords of the parabola "y^(2)=4ax" s: "," (i) "(2a+x)y^(2)+4a^(3)=0," (B) "a=2," (B) "2" ."]]