part b) I subbed the values into the tangent and got the values of t as 4 and -1, which are correct. However I was unsure of what to do here so I looked at the solutions and they subbed the values of t into the point P, and i'm not sure why, Is it because P has the parametric equations? as in x = at^2 and y = 2at? So P is just a general point on the parabola? If not then why into P?