In (1) triangle ABC, the coordinates of all three points can be obtained. Using cosine theorem, we can get that cos∠ACB= 1/ radical number 5, tan∠ACB=2, and the real point p is point a;

(3) Similarly, point B is point P..

Note: (2) The coordinate of the lowest point of the parabola is Q( 1, -4), the triangle CQB is a right triangle, C is a right angle, and tan∠QBC= 1/3, so if Question 2 asks tan∠PBC= 1/3, then Q is the point P.

If correct, it can be used as an auxiliary line. If the origin is crossed, the vertical line in BC will intersect with QB at point M (2, -2), and the extension line of CM(y=x/2-3) will intersect with parabola and point P3 (5/2, -7/4), which is what we want.