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Use a 40 cm long wire to form a rectangle. What's the area of the rectangle?
Let length a and width b be equal
2（a+b）=40
a+b=20
b=20-a
Area s = AB = a (20-a) = 20a-a ^ 2
When a = b = 10, the largest area is s = 100
Use 60 cm long wire to form a rectangle, so that its width is 2 / 3 of its length
Length + width = 60 △ 2 = 30cm
Length = 30 (1 + 2 / 3) = 18 cm
Width = 30-18 = 12 cm
Area = 18 × 12 = 216 square centimeter
Use 60 cm long wire to form a rectangle, so that the length is 6 cm more than the width. What is the area of the rectangle?
Width = (60 ﹣ 2-6) ﹣ 2 = 12cm
Length = 12 + 6 = 18 cm
Area = 12 × 18 = 216 square centimeters
Use a 6.28 decimeter iron wire to form a square and circle. The circumference of the circle is () decimeter? How many square decimeters is the area?
emergency
Circumference of circle = 6.28
Area of circle: 6.28/3.14/2
=6.28/6.28
=1dm
=1x1x3.14
=3.14cm2
Use a 12.56 cm long wire to form a square. The area of the square is______ Square centimeter; if the wire is used to form a circle, what is the area of the circle______ Square centimeter
(1) 12.56 △ 4 = 3.14 (CM) 3.14 × 3.14 = 9.8596 (cm2). (2) 12.56 △ 2 △ 3.14 = 2 (CM) 3.14 × 22 = 3.14 × 4 = 12.56 (cm2). So the answer is: 9.8596, 12.56
Use a 12.56 cm long wire to form a square. The area of the square is______ Square centimeter; if the wire is used to form a circle, what is the area of the circle______ Square centimeter
(1) 12.56 △ 4 = 3.14 (CM) 3.14 × 3.14 = 9.8596 (cm2). (2) 12.56 △ 2 △ 3.14 = 2 (CM) 3.14 × 22 = 3.14 × 4 = 12.56 (cm2). So the answer is: 9.8596, 12.56
Use a 12.56 cm long wire to form a square. The area of the square is______ Square centimeter; if the wire is used to form a circle, what is the area of the circle______ Square centimeter
(1) 12.56 △ 4 = 3.14 (CM) 3.14 × 3.14 = 9.8596 (cm2). (2) 12.56 △ 2 △ 3.14 = 2 (CM) 3.14 × 22 = 3.14 × 4 = 12.56 (cm2). So the answer is: 9.8596, 12.56
Use a 51.4cm wire to form a semicircle. What is the area of the semicircle?
The radius of the semicircle
=51.4/（3.14+2）、
=51.4/5.14、
=10 cm
The area of this semicircle is
3.14*10*10/2、
=157 square centimeters
How much is the area of a square surrounded by 60 cm long iron wire? What is the perimeter of a rectangle?
OK, I'll take 30 points
Side length = 60 △ 4 = 15 cm
Area = 15 × 15 = 225 square centimeter
The circumference of a rectangle is 60 cm
Use a piece of iron wire to form a square. The side length of the square is 471 cm. If you use this piece of iron wire to form a circle, how many cm is the diameter of the circle?
471 × 4 / 3.14 = 1884 / 3.14 = 600 (CM) a: the diameter of this circle is 600 cm
RELATED INFORMATIONS
- 1. 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?
- 2. 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?
- 3. A 128 cm long iron wire is enclosed into a rectangle according to the ratio of length to width of 5:3. How many square centimeters is the area of the rectangle?
- 4. ① What is the area ratio of a square to a circle if the perimeter of a square and a circle are equal? ② If the area of a square is 314 square centimeters, the area of a circle is______ Square centimeter
- 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. If you want to cut a rectangular iron sheet with an area of 150cm2 so that its length is 5cm more than its width, the length of the rectangle is______ Cm in width______ cm．
- 7. Xiao Li wants to use a square piece of paper with an area of 900 square meters to cut a rectangular piece of paper with an area of 800 square meters along the direction of the side, so that the ratio of length to width is 5:4. I don't know if it can be cut out, but I'm worried. Xiao Ming sees it and says, "don't worry, You must be able to use a large piece of paper to cut a small piece of paper. "Do you agree with Xiao Ming? Can Xiao Li use this piece of paper to cut a piece of paper that meets the requirements?
- 8. A rectangle with a square bottom surface, if the height is reduced by 2 cm, then the surface area will be reduced by 64 square cm. How much cubic cm is the volume reduced? Every step is best written clearly
- 9. One is just cut into two squares, and the surface area increases by 32 square centimeters. How many cubic centimeters is the volume of this rectangle? Come on,
- 10. There are two cylinders with equal base area. The height of the first cylinder is 4 / 7 of that of the second. The volume of the first cylinder is 24 cubic centimeters There are two cylinders with the same base area. The height of the first cylinder is 4 / 7 of that of the second cylinder. The volume of the first cylinder is 24 cubic centimeters. How many cubic centimeters more is the volume of the second cylinder than that of the first cylinder? Ask this type of questions to explain~ Give me more math problems
- 11. 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?
- 12. 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?
- 13. 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?
- 14. 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?
- 15. 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
- 16. 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
- 17. 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
- 18. How many square centimeters is the area of a circle
- 19. 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 ()
- 20. 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?