Class: Name: Seat Number: Grade:

Fill in the blanks. (0.5 points for each space, *** 13 points)

1. When drawing a circle, a fixed point is called (), the line segment from () to () is called radius, and the line segment whose two ends pass through () on the circle is called ().

2. When drawing a circle with a compass, the distance between two feet of the compass is a circle ().

3. In the same circle, there are () diameters and () radii; The length of the diameter is () times the length of the radius.

No matter how big or small a circle is, its circumference is always greater than () times its diameter. This fixed multiple is called () and is usually represented by the letter ().

5. The length of the curve forming a circle is called () of the circle.

6, known circle diameter d, circumference c = (); The radius r and circumference c of a circle are known.

7, the circle is () graphics, it has a () axis of symmetry.

8. Fill in the form:

Name radius (r) diameter (d) perimeter (c) area

Bicycle tires 5 decimeters

Clock face 2 cm

The round flower bed is 62.8 meters.

Third, choose. (8 points)

1, () determines the size of the circle, () determines the position of the circle.

A. Diameter B. Center C. Radius D. Perimeter

2. There is only one axis of symmetry in () below, but there are countless axes of symmetry in ().

A. square B. isosceles triangle C. circle D. rectangle

3. If a circle knows its perimeter, to find its area, first ask for the circle's ().

A. diameter B. radius C. Pi

4. When the radius of a circle is enlarged by 3 times, its perimeter () and area ().

A. Expand by 3 times B. Expand by 9 times C. Reduce by 3 times D. Reduce by 9 times

5. The circumference of a circle is 6.28 meters and the area is () square meters.

A.2 B. 3. 14 C. 1

Fourth, the judge. (5 points)

1, the value of pi is 3. 14.

The diameter of a circle is twice the radius.

A circle with a diameter of 7 cm is larger than a circle with a radius of 4 cm.

4. In a circle, any diameter is the symmetry axis of the circle.

5. Two circles with equal perimeters have equal areas.

5. calculation. (28 points)

1, find the perimeter of each circle below. (12)

① ② ③

2. Find the area of each circle or ring below. (16)

① ②

③ ④

Sixth, hands-on operation. (10)

1、

2. Draw all the symmetry axes in the picture below. (5 points)

Seven, solve the problem. (30 points)

The outer diameter of bicycle tire is 0.8m, and it rotates 60 times per minute. How many meters can it advance per minute?

There is an automatic rotating sprinkler on the school lawn with a range of 20 meters. How many square meters of grass can this sprinkler spray at most?

5. The picture on the right is a square with a side length of 8dm. What is the circumference of the largest circle in a square? What is the area?

6. Uncle Li has a 47 1 meter long wire. He is going to circle it in a round cowshed and circle it three times. How many square meters is this cowshed?