∠DBC=20？ , then ∠ a =
3. When Xiao Qiang looked in the mirror, he saw the clothes printed in the mirror:
The words on Xiao Qiang's clothes should be
There are three red balls and several white balls in a pocket. If you find any one,
If the probability of touching a red ball is 0, there is a white ball in the bag.
5. As shown in the figure, the angular bisectors DB and DC of △ABC intersect at
Point d, EF intersects with point d, EF∨BC, if be = 4, cf = 3, ef =
6. The number of torchbearers for the 2008 Beijing Olympic Games reached 265,438+0,780, which was expressed as an appointment by scientific notation (two significant figures were reserved).
7. The approximate value of 3 10/0,000 is accurate and has significant figures.
Xiao Ming sees the clock behind him in the mirror as shown in the picture, so the actual time is
be
10. The Meteorological Observatory predicts that "the probability of precipitation in this city will be 80% tomorrow". For this information, the following statement is correct ().
There will be 80% precipitation in this city tomorrow.
It will rain 80% of the time in this city tomorrow.
It will definitely rain tomorrow.
It is more likely to rain tomorrow.
1 1. As shown in the figure, Party A and Party B start from place A..
Distance and time map of location B.
(1)A and B are km apart.
(2) the average speed of a is km/h.
The average speed of b is km/h.
(3) A leaves an hour earlier than B..
(4) Who gets to B early and how early?
(5) According to the above conditions, please list the equations and find out how long it will take for B to catch up with A.
13. As shown in the figure, at △AB=AC, AB=AC, D is a point above BC, DE⊥AB is at E, DF⊥AC is at F, ① When D is at BC, DE = DF? Explain the reasons; (2) If you don't add auxiliary lines, can you write different conditions from (1) to make DE equal to DF? Please write down two such conditions, but don't explain the reasons.
14. As shown in the figure, in △ABC, ∠B=90? The perpendicular line of the hypotenuse AC intersects BC at point D, and the vertical foot is point E, ∠ C = 40? ,
Find the degree of ∠ bad.
Synthesis (2)
1. The complementary angle of an angle is 135? So what is the degree of this angle?
2. expressed by scientific notation: 0.00000053 =
3. The approximate value of 0.03 10 has a significant number.
4. The approximate value of12500 has two significant figures, which are expressed by scientific notation as follows.
5. Put eight red balls and two white balls in an opaque bag, and Xiao Ming touches a ball at random. The probability that this ball is a white ball is 7. If k 2+ 18k+8 1 is a completely flat road, then the value of k is
8. The following statement is wrong ()
A and 5 are monomial B, and the coefficient and degree of monomial M are 1.
The coefficient of c is d, which is a quadratic monomial.
12. Xiao Wang found that the clock in the mirror showed 2: 15, so the actual time was.
15. the relationship between the area s and the radius r of a circle is s= r2, when the radius
When it changes from 1 to 2, the area of the circle increases.
16. If a card is randomly drawn from a deck of poker with no king, then P (drawn to 5) =; P (draw spades)
18. There are 12 red, yellow and white balls in a bag. Please design a scheme that meets the following conditions:
(1) Pick a ball at random, the probability of getting a yellow ball is the same as that of a white ball, and the probability of getting a red ball is the smallest;
(2) Touching the ball at will has the highest probability of getting a red ball and the lowest probability of getting a white ball;
(3) If you touch a ball at random, the probability of getting a red ball is, and the probability of getting a yellow ball is.
22. A farmer friend took a few kilograms of potatoes to the city to sell. He brought some small change for convenience. After selling some according to the market, he reduced the price. The relationship between the number of kilograms of potatoes sold x and the amount of money in his hand y (including change) is shown in the figure. Answer the following questions with pictures:
(1) How many changes have farmers brought?
(2) What was his price per kilogram of potatoes before the price reduction?
(3) After reducing the price, he sold the surplus potatoes in 0.4 yuan per kilogram. At this time, the money in his hand (including spare money) is 26 yuan. How many kilograms of potatoes did he bring?
24. As shown in the figure, in △ABC, ∠ c = 90, AD bisects ∠BAC, BC= 10cm, BD=6cm, then the distance DE from point D to AB is _ _ _ _ _ _ _ _.
25. In the garden of a class, 53 lottery tickets were prepared, including the first prize 1, three second prizes and five third prizes. Xiao Qiang was the fourth lucky draw. If one of the top three students won the second prize and the other two didn't, the probability of Xiao Qiang winning the prize is ().
A. 10% B. 15%
26. In the following events, the probability of 1 is ().
A, roll the dice and appear at 6 o'clock. B, the sun rises in the east.
C in a few years, there will be a big bang on the earth.
D, the whole school * * 1500 people, two of them were randomly selected, and their birthdays were completely different.
27. Fold the square piece of paper twice, cut out a diamond hole and smooth it, and the resulting figure is ().
28. A car has 48 liters of oil in its fuel tank. Starting from a certain place, each line 1 km consumes 0.6 liters of fuel. If the remaining fuel quantity is set to y (liter), the driving distance is x (kilometer).
(1) Which of the above quantities have changed? What are the independent variables? What is the dependent variable?
(2) Write the relationship between Y and X;
(3) Use tables to show the remaining fuel quantity when the car is driving from the starting point 10km, 20km, 30km, 40km and 50km;
(4) According to the data in the table, explain how the remaining oil quantity changes with the distance;
(5) How many liters of oil is left in this car after 35 kilometers? How many kilometers has the car traveled with the remaining fuel 12 liter?
Please estimate how many kilometers this car can run without refueling.