5. The area of rectangle and square is1225m2, and the area of circle is1256m2. Which of these three figures has the largest circumference?
6. Given that the perimeter ratio of two similar polygons is 1:2 and the sum of their areas is 25, what are the areas of these two polygons respectively?
7. A square cardboard with a side length of 4 cm, with its opposite side as the diameter, what is the circumference of the remaining figure after cutting off two semicircles?
8. The circumference of a circle is 12.5 decimeter. If the radius is increased by half, how much will the area increase and how many square decimeters will it increase?
9. The circumference of a circle is 12.56 decimeter. If the radius increases 1/2, how much does the area increase? How many square decimetres have you increased?
10. An annular iron sheet with an inner radius of 10 cm and an outer radius of 15 cm. How many square centimeters is its area?
1 1. Circumference of annular flower bed in street garden18.84m.. What is the area of the flower bed?
12. The diameter of the radar circular screen is 40 cm. How many square meters is its area?
13. A circular pool with a circumference of 37.68 meters. What is its diameter and radius?
14. For a right-angled trapezoid, the ratio of the upper base to the lower base is 5: 2. If the upper bottom is extended by 2 meters and the lower bottom is extended by 8 meters to become a square, what is the area of the original trapezoid?