Known: as shown in the figure, in ▱ ABCD, point E is on ad, connect be, DF ‖ be, intersect BC at point F, AF and be at point m, CE and DF at point n. verification: the quadrilateral mfne is a parallelogram

It is proved that: ∵ quadrilateral ABCD is a parallelogram, ∵ ad = BC, ad ∥ BC, and ∵ DF ∥ be, ∵ quadrilateral BEDF is a parallelogram, ∵ de = BF, me ∥ NF, ∵ ad-de = bc-bf, that is AE = CF, and ∵ AE ∥ CF, ∵ quadrilateral afce is a parallelogram, ∵ MF ∥ ne, ∥ quadrilateral mfne is a parallelogram

Who can give a set of eighth grade mathematics "quadrilateral" training questions, to be rare!

The answer of stage training a and quadrilateral a
. write it briefly
1 has a set of adjacent edges equal__ It's a diamond
2 diagonal_ The parallelogram of is a rectangle
3 in RT △ ABC, if angle a = 90 °, ab = 3, BC = 4, then AC=
If four points a, B and C can form a triangle, → AB + → BC + → CA=_ [→ is a vector]
A [or arbitrary] vector expression whose direction cannot be determined_
6→AB+→BC-→AC=_
If the two adjacent sides of a rectangle are 2 and 2 root sign 3, then the sharp angle between the diagonals is 2__ degree
The axis of symmetry of the 8 diamond is_
9 in the parallelogram ABCD. AB = 6, BC = 7, the height of AB side is 4, then the height of BC side is 4
The perimeter of a 10 diamond is 40, the length of one diagonal is 16, and the length of the other diagonal is 40
11 known square in ABCD. The intersection of AB = 6, AC, BD and O is Ao=_

1. Parallelogram
2. Equal
3. AC = root 7
4.→0
5.→0
6.→0
7.60 degrees
8. Its diagonal
9.24/7
ten point one two
11.3 root 2

Given y = 2x, z = 2Y, then x + y + x equals ()

Y = 2x, z = 2Y, then x + y + x equals ()
z=2y=4x
x+y+x=4x
x+y+z=7x

Draw a parabola. How many grid points can it pass through in the 8X8 grid? Why?

Thank you. This is the answer of the third day of junior high school
Programming for you, there are 8 points:
(0,0)(1,3)(2,5)(3,6)(4,6)(5,5)(6,3)(7,0)
The equation is: y = - 0.5x + 3.5x
But I don't know how to supplement it with the thinking of grade three
The coordinates of the upper points are calculated with the lower left corner as (0,0)
Well, here's an idea:
First of all, there will be no more than 9 points, because according to the definition of the function, one X cannot correspond to more than two ys, and the value of X can only be up to 9
So, let's say we've crossed nine points
To sum up, the parabola to meet the demand can pass through 8 points at most
Let's assume that it can pass through 8 points, then according to the above idea, its axis of symmetry can only be outside the grid or x = 3.5 (if x = 4, it will pass through odd points). We consider that the axis of symmetry is x = 3.5 (this is easier to find), then according to the above idea of B, it must pass through (0,0), (3,6), (4,6) and (7,0), and the obtained equation is y = - 0.5x + 3.5x, which is verified to pass through 8 points
Therefore, at most eight points are crossed
Winter has passed

The symmetry axis of quadratic function y = 4x square - MX + 5 is X=_ 2, then when x = 1, the value of Y is

M = - 16 y = 4x square + 16x + 5 x = 1 y = 25=_ 2 "is" x = - 2 "!

When x = - 4, the value of quadratic trinomial ax squared - 4x - 1 is - 1. When x = 5, the value of quadratic trinomial is?

When x = - 4, the square of quadratic trinomial ax - 4x - 1 is - 1
a×16＋16－1=－1
a=－16
When x = 5, ax & # 178; - 4x-1 = - 16 × 25-4 × 5-1 = - 421

Given a + B + C = 1, a 2 + B 2 + C 2 = 2, find the value of AB + BC + ca

∵ a + B + C = 1, ∵ a + B + C) 2 = A2 + B2 + C2 + 2Ab + 2BC + 2Ac = 1, ∵ A2 + B2 + C2 = 2, ∵ 2 + 2Ab + 2BC + 2Ac = 1, the solution is ab + BC + AC = - 12

As shown in Figure 1, ⊙ o, AB is the diameter, C is the point on ⊙ o, ⊙ ABC = 45 °, isosceles right triangle DCE, ⊙ DCE is a right angle, and point D is on line AC. (1) prove that B, C, e are collinear; (2) if m is the midpoint of line be, n is the midpoint of line ad, prove that Mn = 2om; (3) mark △ DCE as △ d1ce1 (Figure 2) after rotating a (0 ° < α < 90 °) counterclockwise around point C The midpoint of line be1, N1 is the midpoint of line AD1, is m1n1 = 2om1 true? If not, please prove; if not, give reasons

(1) It is proved that: ∵ AB is the diameter, ∵ BCA = 90 °, while in isosceles right triangle DCE, ∵ ACB = ∵ DCE = 90 °, ∵ BCA + ∵ DCE = 90 ° + 90 ° = 180 °, ∵ B, C, e are collinear; (2) connect BD, AE, on, extend BD intersection AE to F, as shown in Figure 1, ∵ CB = Ca, CD = CE

777 * 777, how to calculate the most accurate? What is the equivalent?
Sorry, I forgot to write it. What is the most accurate estimate? What's the equivalent?

1.（800－23）^2=640000-46*800+529=603729
2.49*111^2=12321*49
= 12321(50-1)=1232100/2 - 12321=616050-12321=603729

Known: as shown in the figure, in ▱ ABCD, point E is on ad, connect be, DF ‖ be, intersect BC at point F, AF and be at point m, CE and DF at point n. verification: the quadrilateral mfne is a parallelogram