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Xinxing kindergarten has a circular playground. The perimeter of the playground is 31.4m. Later, it was expanded and the radius increased by 1m. How many square meters has the area increased after the expansion
The original radius is 31.4 △ 2 △ 3.14 = 5m
So then it was 5 + 1 = 6 meters
The area is 3.14 × 6 × 6 = 113.04 square meters
There is a round lawn with a circumference of 62.8 meters. It is going to be equipped with automatic rotary sprinkler for irrigation. There are three kinds of devices with a range of 20 meters, 15 meters and 10 meters. Which one do you think is more suitable? Where is the best place to install it?
62.8 ﹣ 3.14 ﹣ 2, = 20 ﹣ 2, = 10 (m); a: select the device with a range of 10 m; it should be placed at the center of the circle
The range of the lawn automatic rotation sprinkler irrigation device in Century Square is 4 meters to 8 meters. How many square meters can it spray irrigation area?
Area = 3.14 * (8-4-178;) = 3.14 * 48 = 150.72 M2
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