Prove that the two tangents to a parabola from any point on the directix are perpendicular.

Im not sure about this question. I was drawing it out and like.. can you have a line thats tangent to a parabola or wont they all eventually cross it? I think if yes... then wouldnt it be more then 2 tangent lines ? anyway can anyone maybe talk about this problem and maybe point me in the right direction?