1. As shown in the figure, in Rt⊿ABC, AB=3, BC=4, ∠ ABC = 90, passing B is BA 1⊥AC, and passing A 1 is A1b/kloc-. ..... So, please guess that the sum of the areas of all shadow triangles obtained in this way is ().

A.B. C. D。

Two. Fill in the blanks (4 points)

2. As shown in the figure, the area of positive ⊿ABC is known as 1.

In the figure (1), if, then

In Figure (2), if, then;

In Figure (2), if, then;

According to this law, if, then.

1, as shown in the figure, point A is the moving point on the straight line, the passing point A is the △ABC x axis, the vertical foot B and point C are the isosceles right triangle on the Y axis. Please write down the coordinates of all qualified points C.

Reference answers: (0), (0, 1), (0, 0), (0, -3)