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A circular ring, the diameter of the outer circle is 5cm, the radius of the inner circle is 3cm, how many square meters is its area?
Hello: circle area = outer circle area inner circle area outer circle area = 3.14 × 5 & # 178; = 78.5 (square centimeter) inner circle area = 3.14 × 3 & # 178; = 28.26 (square centimeter) circle area = 78.5-28.26 = 50.24 (square centimeter) can also be calculated like this: 3.14 × (5 & # 178; - 3 & # 178;) = 3.14 × 16 = 5
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