![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
How many square centimeters is the area of a circle
Let r cm be the radius
（2+2π）r=16.56
r=3
S circle = π R & # 178; = 9 π≈ 28.26 CM & # 178;
Cut a circle half along its diameter, and the remaining circumference is 4.56cm less than the original circumference. The area of this circle ()
Radius 4.56 △ 3.14-2 = 4cm
Area 4x4x3.14 = 50.24 square centimeter
If you don't understand this question, you can ask,
The area ratio of the big circle and the small circle is 9:1, and the circumference difference is 12.56 cm. What is the area of the small circle?
Let the radius of the large circle be r, and the radius of the small circle be r.3.14 × R × 2-3.14 × R × 2 = 12.56 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 6.28 × (R-R) = 12.56 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp
What is the area of a circle with a circumference of 18.84 meters?
2 π r = 18.84, r = 3
S=πr²=28.27
The area of a circle is 18.84 square centimeters. What is its perimeter?
Let the radius of the circle be X
Then x × x × 3.14 = 18.84
That is, X × x = 6
Then x = root 6
So the perimeter is 2 × π × radical 6 ≈ 15.4cm
Hope to adopt. Happy New Year!
What is the area of a circle with a circumference of 18.84 cm?
（18.84÷3.14÷2）×3.14=28.26
The radius ratio of the two circles a and B is 3:5. It is known that the area of the two circles is 680 square centimeters. How many square centimeters are the areas of the two circles?
If the radius ratio is 3:5, then the area ratio is 9:25
The area of the two circles is 9 / (9 + 25) * 680
25/(9+25)*680
The radius ratio of circle a and circle B is 2:3. The total area of these two circles is 260 square centimeters. How many square centimeters are the areas of circle a and circle B?
Experts: it is known that the radius ratio of circle a and circle B is 2:3, so the radius ratio of circle a and circle B is (2 & sup2;): (3 & sup2;) = 4:9 (area ratio = square ratio of radius) the area of circle a is 260 △ (4 + 9) × 4 = 80 (square centimeter) the area of circle B is 260 ± (4 + 9) × 9 = 180 (square centimeter) or 260-80 = 180 (...)
The radius ratio of the two circles a and B is 3 ∶ 5. It is known that the sum of the areas of the two circles is 680 square centimeters. What are the areas of the two circles?
The area ratio of the two circles is 3 & sup2;: 5 & sup2; = 9:25
9+25=34
The area of a is 680 × 9 / 34 = 180 square centimeter
The area of B is 680 × 25 / 34 = 500 square centimeter
The radius ratio of the two circles a and B is 3:5. It is known that the area of the two circles is 680 square centimeters. How many square meters are the areas of the two circles?
Please explain how this is done, mainly the process and method!
Since area = 3.14 * square of radius
Therefore, if the radius ratio of the two circles is 3:5, the area ratio of two circles is 9:25
680/（9+25）=20
Therefore, the area of a is: 9 * 20 = 180 square centimeter = 0.018 square meter
Area B: 25 * 20 = 500 square centimeter = 0.05 square meter
RELATED INFORMATIONS
- 1. The radius ratio of the two circles is 3:5. The total area of the two circles is 680 square centimeters. What is the area of the two circles? fast
- 2. The area of a circle is 78.5 square centimeters. Divide it into 16 parts. What are the small fan-shaped area and perimeter of each part
- 3. If a piece of square paper with a circumference of 12 decimeters is used to cut into the largest circle, then the circumference of the circle is 12 decimeters______ Decimeter
- 4. On a square board, it is the largest circle next to it. The perimeter of the board is known to be 120 decimeters. How many square decimeters is the area of this circle?
- 5. Use a 54 cm long wire to form a rectangle. If the length is twice the width, what is the length and width of the rectangle? What's the area?
- 6. A wire is surrounded by a circle with a diameter of 4cm. If it is surrounded by a rectangle, the length of the rectangle is 6cm, then the width of the rectangle is () cm Urgent! According to the sentence "the width of a rectangle is the radius of a circle" in the book, I am right! Asked the teacher only said that this circle has two diameters! What's the matter There are three options A2CM B0．56CM C0．28CM I choose a, but the teacher said to choose C, what's the matter?
- 7. A piece of iron wire is 24 meters long. It should be enclosed into a rectangle. The length is 1.4 times the width. The area of this rectangle is () square meters?
- 8. Use a 40 cm long wire to form a rectangle. What's the area of the rectangle?
- 9. Use 60 decimeter long wire to form a rectangle. The ratio of length to width of the rectangle is 3:2. What's its area?
- 10. Circle the 128 cm wire into a rectangle so that the length is 18 cm more than the width. How many cm are the length and width?
- 11. The radius of the small circle is 2.5cm, the diameter of the large circle is 15cm, the ratio of the circumference of the small circle to that of the large circle is () and the ratio of the area of the large circle to that of the small circle is ()
- 12. The perimeter of a square is equal to that of a circle. Given that the side length of a square is 3.14 cm, what is the radius of a circle? What's the area in square centimeter?
- 13. The radius of a circle is 2 cm. How many square meters is the area of the circle
- 14. The radius of the circle increases four times, and the area of the circle increases () A. 8B. 12C. 16
- 15. Cut out the largest circle in a rectangle 6cm long and 4cm wide. The circumference of the circle is______ The area is______ There is still an area left______ ．
- 16. If the radius of a circle is a centimeter and 2: a = A: 3, the area of the circle is () square centimeter A. 23 π B. 6 π C. 6D
- 17. A ring with an inner diameter of 5cm and an outer radius of 3cm. The area of the ring is______ cm2．
- 18. The outer diameter of a ring is 1.5cm, and the inner diameter is 1cm. What is the area of the ring?
- 19. The outer radius and inner diameter of a ring are 5cm, and the area of the ring is () square cm?
- 20. There are three small circles in the diameter of the big circle. The diameter of the big circle is 5cm, and the diameter of the small circle is 2.5 cm, 1.5 cm and 1cm respectively. The sum of the circumference of the big circle and the three small circles is compared After comparison, which is longer? Which is shorter?