1. Choose carefully (each question has only one correct answer, with 3 points for each question and * * * 30 points).

1. The following statement is true ().

(1) Isoangle is antipodal angle; (2) There is one and only one straight line parallel to the known straight line; (3) Two straight lines perpendicular to the same straight line are parallel to each other; (4) Two straight lines are cut by the third straight line, and the same angle is equal; 0 (B) 1 (C)2 (D)3。

2. The river flows in the same direction after turning the bay twice, so the angle of turning the bay twice may be ().

(a) Turn 50 degrees to the right for the first time and 130 degrees to the left for the second time;

(b) Turn left 5 0 degrees for the first time and 130 degrees for the second time;

(c) Turn right 50 degrees for the first time and 50 degrees for the second time;

(d) Turn left 50 degrees for the first time and right 50 degrees for the second time.

3. As shown on the right, the condition for not judging AB‖CD is ().

(A)∠b+∠BCD = 1800； (B)≈ 1 =∠2； (C)∠3 =∠4； (D)∠B=∠5。

4. It is known that ∠A and ∠B are complementary, while ∠B and ∠C are complementary. If ∠ A = 50, the degree of ∠C is ().

(A)40(B)50(C) 130(D) 140

5. In the following categories, the one that cannot be calculated by the square difference formula is ().

(A) (B)

(C) (D)

6. Known to be completely flat, the value of k is ()

Article 6, paragraph 2, item 3 to article 6, item 4

7. The probability that the puppy walks up and down on the square brick as shown in the figure and finally stops on the shadow square brick is ()

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

8. In the following statement, the correct one is ()

(a) Approximation 5.0 has the same accuracy as approximation 5.

(b) Approximation 3. 197 is accurate to one thousandth and has four significant figures.

(c) About 5000 and about 5000 have the same accuracy.

(d) The significant figures of similarity number 23.0 and similarity number 23 are both 2 and 3.

9. As shown in the figure ∠2+∠3 = 180∠2 = 70∠4 = 80, then ∠ 1= ().

70(B) 1 10(C) 100(D)80

10. As shown in the figure, the straight line EF intersects with CD and AB in m and n respectively, and EMD = 65.

∠ MNB = 1 15, then the following conclusion is correct ().

(A)A =∞C(B)∞E =∞F(C)AE‖FC(D)AB‖DC

2. Fill in the form carefully (3 points for each question, *** 15 points)

1 1. 10 Students are going to have an outing on May 1st. If one of them chooses to bring 20 sausages, the probability of Xiao Liang being selected among 10 students is _ _ _ _ _ _ _.

12. The mathematical formula shown in the figure is 12.

13. As shown in Figure (3), if ∠ 1=620, ∠ 2 = _ _ _ _ _ degrees.

14. As shown in the figure, AB⊥AC and AD⊥AE have _ _ _ _ complementary angles.

Chinese and English contrast

D

A F

15. As shown in the figure, the black and white hexagonal floor tiles are combined into several patterns according to the following rules, so the white floor tiles in the nth pattern have _ _ _ _ _ _ _ _ _ _ _ _ _.

3. Do it seriously (***55 points)

16.(5 points) A store held a prize-winning sales activity, and those who bought more than 100 yuan were given a pair of lottery tickets. 10000 lottery tickets, the grand prize 1 ticket, the first prize1ticket, and the second prize1ticket. If a person's shopping just exceeds 100 yuan, what is the probability of winning the first prize, the first prize, the second prize and the prize?

17.(5 points)

18.(6 points) The values of x= and y=- 1 are known.

19.(6 points) Which of the following events are uncertain, inevitable and impossible?

(1) At standard atmospheric pressure, when the temperature reaches 100C, water will boil; (2) Without water, seeds germinate; (3) Randomly select five people from a class, all of whom are boys. (4) It will rain in this city tomorrow; (5) Turn on the TV, a news broadcast is being broadcast; (6) The reciprocal of a positive number is itself.

A: The uncertain events are: the inevitable events are:

The impossible events are:

20. as shown in the figure, a‖b, b‖c, write the equivalent relationship of the angles in the figure. (Write only the conclusion. If you write the right one, you will get one point, with a maximum of eight points. )

2 1.(8 points) As shown in the figure, ∠ L = ∠l=∠2, DE⊥ BC, AB⊥BC, then ∠A=∠3? Explain why. (Please point out the basis of each step of reasoning)

Conclusion: ∠A equals ∠3 for the following reasons:

Ab⊥bc∵de⊥ BC (known)

∴∠DEC=∠ABC=90()

∴DE‖BC()

∴∠ 1=∠A()

British Columbia also offers the following products:

∠2=∠3( )

∠∠L =∠2 (known)

∴∠A=∠3 (equivalent substitution)

22.(8 points) An opaque bag contains two white balls and 1 red ball, and everything is the same except the color.

(1) Xiao Ming thinks that after mixing evenly, you can find any ball, either a white ball or a red ball, so you can also shape a white ball and a red ball. Do you agree with him? Why?

(2) After mixing evenly, find a ball from it and find the probability that it is not a white ball;

(3) How to add a red ball if the probability of finding it is equal to?