Prove that Tangent Line Bisects Angle?

the solution lies in the fact that at Q(a,b) the tangent line has slope = to 2a since the first derivative of y = x� is 2x so the line thru Q is y-b = 2a(x - a), just look at where it crosses the directerix, and you have the answer. The normal line in the neg inverse of 2a or -1/2a. Good luck, L*