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The first semester mid-term exam of the first volume of eighth grade mathematics

Answer (quantity): 100.

Choose one carefully first (3 points for each small question, 30 points for * * *).

1, in real numbers, 0.3 1,-1, (0.808008)0, and the irrational number is ().

1 (B)2 (C)3 (D)4。

2, in the following graphics, not only is the axial symmetry graphics, but also is the central symmetry graphics ().

3, the following calculation is correct ()

(A)+=； (b) and:

(c) and: (4)

4. The floor tiles sold in the shop have the following shapes: ○ 1 regular triangle ○2 square ○3 regular pentagon ○4 regular hexagon. Only choose a kind of floor tile embedded in the ground, the available floor tiles are ().

(A) 1 species (B)2 species (C)3 species (D)4 species.

5, as shown in the figure, type A becomes type B, which requires ().

(a) rotation and translation (b) translation and symmetry

(c) rotation, symmetry (d) rotation, rotation

6. If the sum of the inner angles of a polygon is three times the sum of the outer angles, then the polygon is ().

(a) octagon (b) nonagon (c) decagon (d) dodecagon.

7. The hypotenuse of a right triangle is 2 longer than the right side, and the other right side is 6 longer, so the hypotenuse length is ().

(A)8(B) 10(C) 12(D) 14

8. If the value of x-y is ()

(A)3 (B)-3 (C) 1 (D)- 1

9.∠A and ∠C are a set of diagonal angles of rectangular ABCD, then ①∠A and ∠C are equal; ② < a and < c are complementary; ③ A is a right angle; (4) c is a right angle. In the above conclusion, () is correct.

1 (B)2 (C)3 (D)4。

10 As shown in the figure, after a rectangular piece of paper is folded along EF, points D and C fall at the positions of D' and C' respectively. If ∠ EFB = 65, ∠AED' is equal to ().

(A) (B) (C) (D)

Second, fill in patiently (3 points for each small question, 30 points for * * *)

The arithmetic square root of 1 1 is _ _ _ _ _.

12, waist of isosceles trapezoid ABCD = CD = 6, AD=4, BC= 10, then ∠ B = _ _ _.

13, if x < 0, then = _ _ _ _ _.

14, calculation: = _ _ _ _ _.

15, AB = AC as shown in the figure, then the number represented by c is _ _ _ _ _ _ _.

16. There is a 5-meter-long ladder frame leaning against the wall of the building, and the horizontal distance between their bottom and the ground is 3 meters, so the height that the ladder can reach the building is _ _ _ _ _ _ _ _.

17. If the error is less than 10, the estimated size is.

18, six kinds of decorative materials are regular polygons with internal angles of 60, 90, 108, 120, 135, 140 respectively, which can be densely laid.

19, the quadrilateral ABCD, AB=CD is known, and the condition _ _ _ _ _ is determined as a parallelogram.

20. The perimeter of the parallelogram is 25, the distance between the two groups of opposite sides is 2cm and 3cm respectively, and its area is _ _ _ _.

Third, be patient (***40 points)

2 1, simplification: (6 points for each question)

( 1)、 ; (2)、 .

(3) ; (4)

22.(8 points) In a square ABCD, E and F are points on AB and BC respectively, and AE = BF. So AF=DE? Tell me why.

23.(8 points) As shown in the figure, it is known that in ABCD, points E and F are on AD and BC respectively, EF bisects diagonal AC vertically, and the vertical foot is O. Try to explain that the quadrilateral AECF is a diamond.

Volume B (50 points)

I. Fill in the blanks (20 points)

1,4. If the square root of a positive number is sum, then this positive number is.

2. Satisfy -< x