Is the area of a circle 20 cm in diameter equal to the sum of two circles 10 cm in diameter?

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• 1. The diameter of the outer circle of a ring is 10 cm, and the diameter of the inner circle is 8 cm. What is the area of this circle
• 2. There is a ring (as shown in the figure). Its inner circle diameter is 6cm and outer circle diameter is 10cm. What is the area of this circle?
• 3. If the diameter of a circle is increased by 1 / 10, how many parts of the area of the circle will be increased
• 4. The diameter of a circle increases by 10%, and the area of the circle increases by ()%
• 5. The sum of the radii of two circles is 12 cm. The diameter of one circle is 10 cm. What is the area of the other circle?
• 6. The sum of the areas of two circles with a diameter of 10 cm is equal to that of a circle with a diameter of 20 cm______ ．
• 7. If the area of a circle is 2 π cm square, find the radius of the circle
• 8. If the radius of a circle increases by 1 / 5, its area will increase by 88 square decimeters Very urgent! There is a prize for correct answer Double reward for the right person
• 9. If the radius of the circle is increased by 15, its area will be increased by 88 DM2
• 10. If the radius of a circle is reduced by 1 / 3, its area will be reduced by 25 square decimeters
• 11. There is a triangle in a circle. The area of the triangle is 15 square centimeters. What's the area of the circle?... but why is the area of the triangle the bottom?
• 12. Why is the area of a circle with a diameter of 10cm larger than that of a circle with a diameter of 10cm * 10cm?
• 13. Given the diameter of the circle, find the area of the circle: 1) d = 10cm; 2) d = 30cm; 3) d = 100cm; 4) d = 12m
• 14. As shown in the figure, the area of the circle is 21.98 square centimeters, so how many square centimeters is the area of the square?
• 15. As shown in the figure, the area of a square is 16 square centimeters There are squares in the circle!
• 16. As shown in the figure, the area of a circle is 31.4 square centimeters, and the area of a square is______ ．
• 17. Known circle area is 9.42 square centimeter, seek shadow part area A graph is a circle. There is a square in the quarter circle. Find the area beyond the quarter circle
• 18. There are two piles of coal. There are 20 tons of coal in pile a and 17.5 tons of coal in pile B. 2 tons of coal in pile a and 1.5 tons of coal in pile B are used every day. How many days The remaining equality equation solution of the last two piles of coal
• 19. A and B cars are going from AB to ab at different speeds. They meet on the way. The meeting place is 70km away from B Online, etc The two cars of a and B travel from AB to ab at different speeds. They meet on the way. The meeting place is 70km away from B. after meeting, the two cars continue to advance at the same speed, return immediately after reaching the destination, and meet again on the way. At this time, the meeting place is 50km away from A. It is known that the time from the first meeting to the second meeting is 4 hours. How about the speed of the two cars?
• 20. A car at 45 kilometers per hour from a to B, 3 hours a journey of 57, how many kilometers does the car have to travel to reach B?