Before you do the problem, I remind you that you won't (after some thinking), you can put it aside first. Don't waste time on some difficult problems at this time.

Inverse calculation of p coordinate;

Quadrilateral PAM has the smallest area-triangular PAM has the smallest area-PA has the smallest length-PM has the smallest length.

The minimum length of PM is 2.

Let p (x, y) and y 2 = 4x.

The length of PM2 = (x-3) 2+Y2 = (x-3) 2+4x = x2-2x+9 is the smallest.

x= 1

P( 1，2)

Calculate the coordinates of A and B forward, and then calculate the AB equation (or calculate the slope first by using the vertical relationship between AB and PM to simplify the calculation).

The calculation is simplified.