The tangent P(3,9) on the curve y = x^2, cuts the x-axis at T and PN is perpendicular to the x-axis. Find the length of TN.
So far I have:
dy/dx = 2x
dy/dx = 6
y - 9 = 6(x - 3)
y = 6x - 9
Making point T (3/2, 0), but how do you find point N?
Thank you.