How many centimeters is the circumference of the rectangle? I know the answer is 140, but I don't know how to get it

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• 1. Square and circle with equal circumference, which is big? Please explain why! (I know it's a circle, just want to know why.)
• 2. There is a square. If the side length is reduced by 5 cm, the area will be reduced by 125 square cm There is a square. If the side length is reduced by 5 cm, the area will be reduced by 125 square cm. How about the square area?
• 3. The length of a rectangle is x meters and the width is y meters. If the width remains the same and the length decreases by 3 meters, then its perimeter decreases by () meters and its area decreases by () square meters
• 4. Put two rectangles 8 cm long and 4 cm wide into a square. What's the perimeter of the square and what's the perimeter of a large rectangle?
• 5. A piece of square glass is cut off by 12 cm on one side and 8 cm on the other. The remaining rectangular area is 1760 square cm less than the original area. How long is the original side of this square glass?
• 6. When the length of a rectangle is reduced by 8 cm and the width by 4 cm, the area will be reduced by 92 square cm, leaving a square. What is the area of a square
• 7. A rectangle is 8 cm long. If its length is reduced by 3 cm, it becomes a square. How many square centimeters has its area been reduced?
• 8. If a circle with a diameter of 8 cm is reduced by 2 cm, its perimeter and area will be reduced by () cm and () cm respectively
• 9. The bottom of a triangle is 10 centimeters, and its area is 80 square centimeters. How many centimeters should the bottom be shortened to reduce its area by 20 square centimeters?
• 10. The bottom of a triangle is 10 cm, and its area is 80 square cm. How much should the bottom be shortened to reduce its area by 20 cm
• 11. The length of the oblique side of a right triangle is 20cm, and the two right sides are respectively suspended 16cm and 12cm. What is the height of the oblique side
• 12. There is a piece of paper with a length of 6.5cm and a width of 2cm, as shown in the figure. Please divide it into 6 pieces, and then put it together into a square. (requirement: draw the dividing line in the figure, and then draw the square and mark the corresponding data)
• 13. As shown in the picture: a rectangular sheet of iron, 30cm long and 20cm wide, subtracting a small square with 4cm side length from four corners, and then folding it along the dotted line to make a box without a cover. How many milliliters is the volume of the box? How much sheet iron is actually used to make the box? (I have no picture, understanding)
• 14. A 20 cm long, 15 cm wide rectangular cardboard, four corners cut side length of 5 cm, do not cover the box, no cover how big cardboard box, can hold how much juice
• 15. : find out the perimeter and area of the figure below! The top is a semicircle, the bottom is a rectangle, the length of the rectangle is 4cm, the width is 5cm Figure out the perimeter and area of the figure below! Above is a semicircle, below is a rectangle, the length of the rectangle is 4cm, the width is 5cm
• 16. It is known that the length of a rectangle is 20cm and the width is 5cm. The area of a rectangle is converted into a square and the perimeter of the square is calculated
• 17. Excuse me: a circle with a radius of 2.5cm is equal to the perimeter of a rectangle. It is known that the length of the rectangle is 4.5cm. What is the area of the rectangle?
• 18. A rectangle is 8cm long and 5cm wide. What are its area and perimeter?
• 19. A rectangle with a square bottom area, the perimeter of the bottom area is 12cm, 5cm, the bottom area of the rectangle is (), the surface area is ()
• 20. If a = 5cm, find the perimeter and area of the square; if a = 7cm, B = 4cm, find the perimeter and area of the rectangle