24. That is to say, after triangles are similar, if the area ratio is 3≤S≤4 (I forgot a little), there is a certain congruence. The angle B = 30 and the angle BCD = 60 in the trapezoidal ABCD connect the diagonal AC.

(1) If diagonal AD=CD, it is proved that △ABC and △ACD have certain congruence.

(2) Is there a certain congruence between △ ABC and △ACD?

25. In right-angle ABCD, AB tangent circle O is in E, AD tangent circle O is in F, AE= radical number 3, and straight line MN intersects rays DA and DC in M and N, respectively, with an angle of DMN = 60°. The distance from d to line MN is d.

(1) Find the arc length EF

(2) If 1≤d≤4, find the positional relationship between the straight line MN and the circle O.

26. The coordinate of point P is (m,-1) (m > 0), and the coordinate origin O is connected with OP. Rotate OP counterclockwise by 90 to get M, where M is a parabola y = ax &；; sup2+bx+c(a≠0)

When (1)m= 1, the parabola passes through (2,2), and the analytical expression of parabola is obtained.

(2)A coordinate is (1, 0), and the intersection of parabola and Y axis is B. If there is only one intersection between straight line AB and parabola, find the shape of △BOM.

You should know the first one!

The second one is ok if it only says one angle and proves that it is not similar.

The first question, you will definitely.

The second problem is to find out what happens when it is tangent. Using the tangent length theorem, it can be proved that there are many 60-degree triangles. Using trigonometric function, we can calculate that the length of d is 2 and 3 numbers, so it is divided into three categories.

Let's not talk about the first question.

The second question (I haven't been right with others, because only I have done it ... so I don't know if it is right or wrong)

P coordinate (m,-1) Find a triangle to rotate, and then rotate it to M( 1, m).

B(0, c) (you should understand this), so you can get the analytical formula of AB as y =-CX+C.

Because there is only one intersection, AX &；; sup2+bx+c=-cx+c

I sorted out the unary quadratic equation △=0, because there is no constant term, so B can be represented by C (the details are forgotten).

Because m is the vertex and the axis of symmetry is x= 1, a can be represented by C.

So as to find the vertex (1, c/2)

B is (0, c)

Look at the relationship between the ordinate. Is there anything you can't do? ?

26 no chart