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The exercise paper of the sixth grade mathematics "the understanding of the circle" of the people's Education Press The faster you come, the more points you get! By tomorrow night, come on, come on!
Section 1: understanding of circle
1、 Fill in the blanks
1. The pattern formed by the minute hand of the clock rotating for one circle is ()
2. The line segment from () to () is called radius
3. The line segment passing through () and () is called diameter
4. In the same circle, all radii (), all radii () are equal, and the diameter is equal to radius ()
5. Use a compass to draw a circle with a diameter of 20 cm. The distance between the two feet of the compass is () cm
2、 Judgment questions (mark "√" for right and "×" for wrong)
1. The bucket is round
2. All diameters are equal
3. The diameter of a circle is twice the radius
4. If the diameters of two circles are equal, their radii must also be equal
3、 Fill in the form
r
1.2 cm
9 cm
1.5 decimeters
d
4 decimeters
0.48 M
Section 2: circumference and area of a circle
1、 Fill in the blanks
1. The circumference of a circle is () times the diameter of the circle,
The circumference of a circle is () times the radius of the circle
2. If the radius of the circle is doubled, the diameter of the circle is () times larger, and the circumference of the circle is () times larger
3. Circumference of semicircle = ()
4. If you know the () of a circle, you can find its circumference
5. Can you find out the length of the path of the fan blade turning one circle? How?
6. A circle with a radius of 3 decimeters has a circumference of () decimeters
7. A semicircle with a diameter of 4cm has a circumference of () square centimeter
8. PI is 3.14, right
2、 Find the circumference of each circle below (unit: cm)
1、 r＝2 r＝3 r＝5
2、 d＝2 d＝3 d＝5
3、 Practical questions
1. The perimeter of the circular pool in front of the exhibition hall is 78.5 meters. What is its diameter and radius?
2. The radius of the front wheel of a road roller is 0.4 M. if the front wheel rotates 6 cycles per minute, it can turn from one end of the road to the other in 10 minutes. How long is the road?
3. With a 20 meter long rope around a tree trunk for six circles, there is still 1.16 meters left. How many meters is the diameter of the tree trunk?
4. A yong road is 47.1 meters long. Xiao Ming is rolling an iron ring on the road. The diameter of the iron ring is 30 cm. How many turns does it take to roll the iron ring from one end of the road to the other?
4、 Calculation
1. Oral calculation:
1×3.14= 3×3.14= 4×3.14=
6×3.14= 8×3.14= 9×3.14=
2. Calculate the area of each circle below. (unit: cm)
3. Fill in the blanks:
Divide a round piece of paper into several equal parts, and then cut it open to form an approximate rectangle
The length is equal to that of a circle, and the width is equal to that of a circle
The area of is ()
4. Judgment:
(1) The area formula of a circle is s = π R2 or S = 2 π R（
Sixth grade Mathematical Olympiad exercises
For a rectangle, one side of a wall is a long side of the rectangle, and the other three sides are surrounded by fences. Given that the ratio of length to width is 5 / 2, what is the width of the fence?
The length of the fence is 9 meters. Please show us the analysis method and the steps. Is there any other method?
Let the solution be x meters wide
5/2X+2X=9
Then x = 2
Because there is a long fence, the length of the fence only includes one long and two wide
A circle with a circumference of 31.4cm is divided into several equal parts to form an approximate rectangle. The length of the rectangle is______ Centimeter, width is______ Cm
The radius of the circle is: 31.4 △ 3.14 △ 2 = 5 (CM), so the length of the rectangle is: 31.4 △ 2 = 15.7 (CM), and the width of the rectangle is 5cm. Answer: the length of the rectangle is 15.7cm, and the width is 5cm. So the answer is: 15.7, 5.5
Math problems of grade 6 in primary school
1. The length of the hour hand of the wall clock is 8cm, and the length of the minute hand is 10cm
2. Find rules 3, 5, 14, 55, 274, (), 11500
3. Xiaoming's clock is now 6 o'clock. In () minutes, the hour hand and minute hand coincide for the first time
When the hour hand turns two times a day and night, the walking distance of the needle tip is 2 * 3.14 * 8 * 2. When the minute hand turns 24 times a day and night, the walking distance of the needle tip is 2 * 3.14 * 10 * 24. Therefore, the simplest integer ratio of their walking distance is 1:15
Question 2: 5 = 3 * 2-1, 14 = 5 * 3-1, 55 = 14 * 4-1274 = 55 * 5-1, so the number in brackets should be 274 * 6-1 = 1643
The minute hand moves 360 degrees (one circle) in an hour, 6 degrees per minute, the hour hand moves 360 / 12 = 30 degrees in an hour, and 0.5 degrees per minute. Now they are 180 degrees apart, so the next coincidence is 180 / (6-0.5) = 32.73
Math problems of grade 6 in primary school (explain to me)
1. There is a fraction. If you add 2 to its denominator, you get 7 / 9. If you add 3 to its denominator, you get 3 / 4. Then the fraction is ()
2. The reciprocal sum of the two numbers is equal to 33 / 140, and the original numbers are () and ()
1. The molecule remains unchanged, 7 / 9 and 3 / 4 are changed into the same molecule
7 / 9 = 21 / 27, denominator of 21 / 27 - 2 = 21 / 25
3 / 4 = 21 / 28, denominator of 21 / 28 - 2 = 21 / 25
Correct calculation: 21 / 25
2. A and B are coprime
1/a + 1/b = 33/140
It can be concluded that a * b = 140, a + B = 33
Two numbers whose product is 140 are:
1*140
2*70
4*35
5*28
7*20
10*14
The mutual qualities are as follows:
1 * 140 and 141
4 * 35 and 39
5 * 28 and 33
7 * 20 and 27
Only 4 and 35 qualified
So the original numbers are (4) and (35)
Do you understand? In fact, I'm also in grade six
Upstairs, the questioner is a sixth grade student, should not have taught such a difficult equation
Ask to write the process clearly and then explain why
The students of class 6 (3) have ordered three kinds of magazines, 80% of them have ordered primary school students' composition, 75% of them have ordered PHS, and 60% of them have ordered youth. What percentage of the students who have ordered all three kinds of magazines can account for the most?
Only 60% of the class at most
Because the number of people who order "Youth" is the least. Even if the people who order "Youth" are two copies, there is no possibility that it is smaller than 60%!
A certain project can be completed by several machines within the specified time. If two machines are added, it will only be completed by 7 / 8 of the specified time. If two machines are reduced, it will be delayed by 2 / 3 hours. Now, how long does it take for one machine to complete the project?
Be sure to write down the whole process
A certain project can be completed by several machines within the specified time. If two machines are added, it will be completed by 7 / 8 of the specified time. If two machines are reduced, it will be delayed by 2 / 3 hours. Now, how long does it take for one machine to complete the project? The time is the original 7 / 8, so the number of machines is the original
Given that the circumference of a semicircle is 61.68 decimeters, find its radius
Pay attention to distinguish the circumference of a semicircle from that of a circle
Let R be the radius
Then 3.14 * r + 2R = 61.68
r=12
If the total amount of work is fixed, what is the proportion between work effect and working hours?
If the total amount of work is fixed, what is the proportion of what and what
If the total amount of work is fixed, what is the proportion of what and what
What is the ratio of difference to difference?
1. Inverse proportion
4. Out of proportion
2... 3... Think for yourself and don't give points
During the promotion, the convenience supermarket will increase the price of a commodity by 60% of the purchase price, then write down the reward, and then sell it by 70% of the price. As a result, each commodity still makes a profit of 15 yuan. Do you know how much the purchase price of this commodity is? (solve the equation)
Let the purchase price be x yuan
X*(1+60%)*70%-X=15
0.12X=15
X=15÷0.12
X=125
The purchase price is 125 yuan
Do not understand can ask, help please adopt, thank you!
RELATED INFORMATIONS
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