Area Perimeter of a Circle Practice Questions, Circumference and Area of a Circle Classic Questions

The little monkey rides around a circle, and the radius of the circle is known to be 10m, how much m is the circumference of this circle?

A child rolls an iron ring, the diameter of this iron ring is 7dm, how much dm is the circumference?

7* A circle made of cardboard has a diameter of 20cm, and how many square centimeters is the area?

r=20 (divided by)2=10cm

10*10*cm²).

The length of the triangle is 16 decimeters, and what is the calculation of its area.

The circumference of the trunk of a tree is centimeters. What is the area of the cross-section of the trunk in this lesson?

1) The radius of a circle is 2 meters, the length of a rectangle is equal to the circumference of the circle, and the width is equal to the diameter of this circle, how much does their area differ? (2) The second hand is 1 cm long, how many centimeters will the tip of the second hand go in 2 hours? (3) The radius of the train's driving wheel is meters, if it turns 300 times per minute, how many kilometers does the train travel per hour?

4) A certain type of washbasin produced by the enamel factory is made of round iron sheets with a diameter of meters, if you produce 800 of this basin per day, how many iron sheets are needed?

Solution: Let the radius of the middle circle be the return r, and the radius of the small circle is r, then the radius of the great circle is (r+r) ,2 (r+r) 2= (r+r),(2 r+2 r) 2= (r+r), so it can be seen that the route chosen by the ants is the same length as the two noisy and quiet places. Liters.

Accurate financial status, operating profit and other aspects, so as to provide certain support for the overall enterprise decision-making quality. However, in the process of continuous development at this stage, the stage assumption is a supplement to the continuing operation assumption, after the development of informatization, the distance between the market and enterprises, enterprises and enterprises has changed to a great extent, and after the distance is continuously shortened, it is more obviously affected by various factors, and the changes may be greater. Information technology can better provide certain support for the financial management of enterprises, in the process of carrying out management work, the accounting period can only be divided into a week, a month or so, to maintain within such a range, can not be too long to set hypothetical periods, but not too short.

This is mainly reflected in the fact that there is a cyclical and continuous economic business of some enterprises, and if the division is too small, the continuity will not be reflected. If the division period is too long, the overall cyclicality will be difficult to reflect. This also means that if the overall environment changes, the content of its assumptions will also change to a certain extent, not too long nor too short, in order to effectively evaluate the overall business performance, and provide certain support and guarantee for future development trends and financial conditions.

In contrast, effective staging has become extremely important at this stage, and in the process of division in general, in order to achieve macro-control and grasp the current situation of the enterprise, it is necessary to adhere to reasonable staging, and its own importance has been significantly enhanced.

The sum of the straight spike paths of the two small semicircles in the figure is exactly equal to the diameter of the large semicircle. Let the diameter of the large semicircle be a, and the diameter of the two small semicircles is b and c respectively, then a=b+c, the route family is noisy 1: l1 = a 2, and the route 2: l2 = b 2 + c 2

b/2+c/2)=πb+c)/2

a/2=l2。

It can be seen that the two routes are of the same length.

The length of the course is equal.

The diameter of the large semicircle can be d, and the diameters of the two small semicircles are d1 and d2 respectively. Obviously, d d1 + d2. Scrambled to do.

The first path is d 2 and the second path (d1+d2) is 2, so the two paths are equal in length. Hope.

In this question, the distance of the two paths should be the same length, the circumference area of the circle is 2 r, and the two kinds of 1 and 2 in your figure are actually the same diameter of the semicircle, so the circumference of the core is also the same.

The first way is to ask for the length of the half arc of the big circle, and the second way divides the big circle into two small circles, and the second way is to ask for the half silver of the two small circles to make the arc longer.

The route chosen by the two little ants is as long as a prestige. The length of the 1 route r, the length of the 2 road stove bridge line (r1+r2) = r. So the two routes are the same.

Perimeter and Area Elimination Graph Practice Questions Name: Find the perimeter and area of each figure: (Unit: m) 1. Slow Score of Opening: 4. Find the modulus of the shaded part (unit: cm).

Perimeter = straight meridian * PAI = radius * 2 * PAI area = radius * radius * PAI 1: There is a fish pond, 1, the circle is a kind of ( ) figure on the plane, and the length of the ( ) enclosed in a circle is called the circumference of the circle. At.

, a circle is a kind of ( ) figure on a plane, and the length of the ( ) enclosed by a circle is called the circumference of the circle. In large and small circles, their circumference is always more than ( ) times the diameter of their respective circles, we call this fixed number ( ) is represented by the letter ( ), it is a ( ) decimal number, in the calculation, generally only take its approximate value ( ).

The perimeter is multiplied by the diameter and the area is multiplied by the square of the radius.

Do you provide questions and I answer them, or do you provide questions and answers?

1: There is a fish pond, its radius is 12 meters, if there are 3 circles of fences around this fish pond, how many meters of fence is needed?

12*2*m) m).

2: A and B are walking opposite each other from the same point in a lake at the same time, and the diameter of the lake is known to be 300 meters, and the speed of A is 81 meters per minute, and the speed of B is 76 meters per minute, so the two meet in a few minutes?

300*m) 942 (81+76)=6 (min).

3: Xiao Ming rode a bicycle from home to school, the diameter of the wheel is meters, it is known that the average rotation of the wheel is 200 times per minute, he took 10 minutes from home to school, and asked how many meters Xiao Ming's home is from the school.

m) m) m) 4: The diameter of the wheels of a car is 1 m. If it turns 400 times per minute, how many minutes does it take to cross a kilometer-long bridge?

km = 2512 m 1 * m) 2512 1256 = 2 (min).

5: Wrap a 10 cm long rope around a straw 10 times, and there are still centimeters left, so how many millimeters is the diameter of this straw?

centimeter) centimeter) centimeter).

Centimeter = 3 mm.

1. Fill in the blanks: 1. A circle is a ( ) figure on a plane, and the length of the ( ) enclosed by a circle is called the circumference of the circle. In large and small circles, their circumference is always more than ( ) times the diameter of their respective circles, we call this fixed number ( ) is represented by the letter ( ), it is a ( ) decimal number, in the calculation, generally only take its approximate value ( ).

2. The diameter of a circle is expanded by 5 times, its radius is expanded by ( ) times, its circumference is expanded ( ) times, and the area is expanded ( ) times.

3. Draw a circle with a circumference of centimeters, and the distance between the feet of the compass is ( ) centimeters.

4. Draw the largest circle on a rectangular piece of paper 6 cm long and 4 cm wide, and the radius of this circle is ( ) cm; If you draw the largest semicircle, the radius of this circle is ( ) cm, the circumference is ( ) and the area is ( ).

5. ( It is called the area of a circle. Divide the circle into several equal parts along its radius r, and after cutting, it can be put together into an approximate ( ) The length of this figure is equivalent to the circumference of the circle ( ) is represented by letters is ( ) The width is equivalent to the circle ( ) is represented by letters is ( ) So the area of the circle s (

2. Judgment: 1. The circumference of the circle is a multiple of the diameter of the circle. （

2. The pi of a small circle is smaller than that of a large circle. （

3. Fold a round piece of paper in half several times, and all the creases intersect in the center of the circle. （

4. If the radius of a circle is expanded by 3 times, its diameter will be expanded by 6 times. （

5. The circumference of the semicircle is equal to half of the circumference of the circle. （

6. After a little point, you can draw countless circles. （

1. A bundle of wires is wound 9 times, each circle is 48 cm in diameter, how many meters is this bundle of wires?

2. The outer diameter of a bicycle tire is 60 cm, and the little red cycling wheel rotates 100 times per minute. How many meters per minute does she ride?

3. Which is longer when the sum of the circumferences of two small circles is compared to the circumference of the great circles? (Write out the process in centimeters).

Circumference = straight warp * pai = radius * 2 * pai

Area = Radius * Radius * PAI

Draw the largest circle in a square, and the area of the circle accounts for the area of the square, (this rule is calculated by calculation).

You can directly multiply the area of the square to get the area of the largest circle.

1. The hour hand of a wall clock is 10 centimeters long, how many centimeters does it take to walk at the top of the hour hand after a day and night?

Walk two laps a day and night.

The distance traveled is: 2*2 r=2*2*cm.

2. Xiao Gang used a decimeter-long rope to wrap around a tree trunk exactly 6 times, what is the circumference of this tree trunk? What is the square centimeter area of a cross-section?

The circumference of the tree is: decimeters.

The radius is: decimeters.

The cross-sectional area is: square decimeters.

3. An iron wire is wrapped around a circular cylinder mouth 3 times, just used meters, how many square meters is the area of this cylinder mouth?

The circumference of this cylinder mouth is: meters.

The radius is: meters.

The area is: square meters.

4. The hour hand of a wall clock is 10 cm long, after 12 hours, what is the area swept by this hour hand?

12 hours walked a circle.

Then the swept area is: r = square centimeter.

5. The bottom surface of a wooden basin is round, and a long meter of iron wire is hooped on its bottom surface, and meters are used at the joint of the iron wire, how many meters is the diameter of the bottom surface of this wooden basin?

The circumference of the bottom surface of this tub is: meters.

Diameter: meters.

6. The hour hand on a clock face is 5 centimeters long, from 8 a.m. to 2 p.m., how many centimeters does the tip of the hour hand go?

From 8 a.m. to 2 p.m., I walked for 6 hours, that is, half a circle.

Then the distance traveled by the tip of the hour hand is: r=cm.

7. An iron hoop is decimeter long, just made into a hoop of a wooden barrel, it is known that the joint of the hoop is 5 cm, what is the outer diameter of this wooden barrel?

The outer circumference of the barrel is: decimeters.

The diameter is: decimeters.

Circumference: 10 times 2 times area: 10 times 10 times square centimeters).

Answer: After a day and night, the top of the hour hand has passed.

In fact, it would be nice to use the formula yourself.

s=πr2c=2πr

First, the practical application of perimeter.

1. Two little ants set off from point A to point B to get food, they chose two different routes, who chose the shorter route?

3. Place the 4 circles as shown in the figure below, and enclose a line segment on the outside, how many centimeters is the length of the line segment outside the figure? (The diameter of the circle is 5 cm).

4. Calculate the perimeter of the shaded part in the figure below. (Unit: m) 5. In the figure below, the area of the shaded part is 40 square centimeters, and the annular area is found.

The answer to the question of the two little ants is the same because they have the same diameter.