1. Substitute the coordinates of point A into the analytical formula to find K=-4. The area of triangular ADC is half that of quadrilateral ABOC, and the area of triangular PDC is half that of quadrilateral PEOD, both of which are 2.

2.AP.DC are parallel, because the areas of triangle APD and triangle PDE are equal, so they are parallel.

3. The diagonal line of the diamond is vertically divided, so the vertical line of AC gets the abscissa of point P -2, and it is substituted into the analytical formula to get the ordinate 2, so P (-2,2).

The diagonal of the isosceles trapezoid is equal to AC=PD=4, so the ordinate of point P is 4 and the abscissa is-1, P(- 1, 4).

The waist of isosceles trapezoid is equal, AC and PD are both waist, AC=PD=4, so the ordinate of point P is -4, and the abscissa obtained by substitution is 1, P( 1, -4).