(2) parabola? "Parabolic triangle" is an isosceles right triangle, [source: Z.xx.k.Com]
The vertex of a parabola? Satisfied.
∴? .
(3) existence.
As shown in the figure, do delta? Where's Delta? About origin? Central symmetry,
Then quadrilateral? For parallel four? Edge shape.
What time? When, parallelogram? It is rectangular.
Again? ,
∴△? This is an equilateral triangle.
Work? What are feet? .
∴? .
∴? .
∴? .
∴? ,? .
∴? ,? .
Set a little? A three-point parabola? , then
Solve it, have to?
∴ What is the expression of parabola? .
25. Solution: (1) As shown in figure 1, square? Just what you want.
(2) Set a square? What is the side length of? .
∵△? Is a regular triangle,
∴? .
∴? .
∴? , that is? No denominator is right. Also correct)
(3) As shown in Figure ②, connect? And then what? . ?
Set a square? Square? What is the side length of? ,
What is the total area of them? And then what? ,? .
∴? .
∴? .
Extension? Turn it in At this point? And then what? .
Are you online? Yes,? .
∵? , that is? .
I) When? When was that? What time? Minimum.
∴? .
Ii) When? The longest time? Maximum value.
Immediately? Maximum sum? Minimum hour? Maximum value.
∵? , known by (2),? .
∴? .
∴? .
[Source: Subject Network]