2. A circle has a diameter of 2m, a circumference of () and an area of ().
3. Dig a circular pool with a diameter of 20 meters, with an area of ().
4. A circle with a circumference of 9.24 decimeters has a radius of () and an area of ().
5. The sector area with a radius of 4 decimeters and a central angle of 120 is () square decimeter.
6. The area of a sector with a radius of 3 decimeters is 4.7 1 square decimeter, and the central angle of the sector is () degrees.
7. A wire with a length of () cm can form a semicircle with a diameter of 4 cm.
8. The area of a circle is 32 square centimeters, and the area of a sector with a central angle of 45 in this circle is () square centimeters.
Second, the judgment question. (Mark "√" for the right and "×" for the wrong. )
1. In the same circle, the radius is equal to 0.5 times the diameter. …………………………( )
2. If the perimeters of a circle and a square are equal, the diameter of the circle is greater than the side length of the square. … ( )
The radius of the big circle is twice that of the small circle, so the area of the big circle is twice that of the small circle. ( )
4. The pi of the big circle is greater than that of the small circle. ……………………………………….( )
A circle with a radius of 2 decimeters has the same circumference and area. ……………………………( )
6. The area of a sector with a central angle of1is. ……………………………………( )
7. The central angle is 96 degrees, and the area of the glyph is the area of the circle ................................. ()
Third, multiple choice questions.
1. In a square with a side length of 10 cm, take the side length as the radius and cut it into a fan shape. Sector area accounts for () of square area.
A.B. C. D。
2. The circumference of a circle is the radius of the circle ()
A.6 times B.2∏ times C.3. 14 times.
Fourth, the application problem.
1. The area of a rectangle is equal to the area of a circle with a radius of 4 decimeters. It is known that one side of a rectangle is 10 decimeter. What's its width?
2. The areas of the two circles are 24cm2 and 3 1 cm2, respectively, and the overlapping area of the two circles is 43cm2. Find the area of the overlapping part.
3. The cross section of a piece of steel is fan-shaped, with a radius of 4 decimeters and a central angle of 45. What is the cross section of this steel?
4. The area of the circle where the fan with a central angle of 75 is located is 48 square meters. What is the area of this fan?
5. The area of the sector is 3 14cm2, and the area of the circle where the sector is located is 1256cm2. What is the central angle of this sector?
6. The area of a sector with a central angle of120 is equal to the area of a parallelogram with a base of 6 cm and a height of 6.28 cm. Find the radius of the sector.
Test 2 (2) Page 49
(5) A number is the reciprocal of B number. After the decimal point of a number is shifted to the left by one place, it is 0.24. What is a b number?
(6) The weight of a person on the moon is equivalent to the weight on the earth. Xiaohua weighs 36 kilograms. If Xiaohua is on the moon, what is her weight? How many kilograms did she lose on the moon than on the earth?
(7) The cement plant originally planned to produce cement 1.500 tons in the first half of the year, but actually completed the planned task in one month. According to this calculation, how many tons did the cement plant produce in the first half of the year than originally planned?
(8) A story book, ***96 pages, Xiao Ming read 43 pages, how many pages are left than this book?
(9) The length of a wire is120m. How many meters were cut off for the first time and the second time? Which time did you cut more? How many meters are there?
A wire is 120 meters long. How many meters did you cut for the first time and how many meters did you cut for the second time? Which time did you cut more?
(1 1) Students attend various classes, and mathematics, composition and English account for the total number. What is the percentage of participants in the total number, English and computer? What percentage of students are English speakers and English speakers?
(12) calculation:++...++
13. Fill in the seven numbers ○ 1, 2, 3, 4, 5, 6, 7 below to make the sum of the three numbers on each straight line equal.