The radius of the outer circle of a ring is 1.5cm, the radius of the inner circle is 1cm, what is the area

The area is 3.14 × (1.5 & sup2; - 1 & sup2;) = 3.925 (CM & sup2;)

The radius of the inner circle of a ring is 4cm, the radius of the outer circle is 5cm, and the area of the ring is ()?

According to the area formula of circle, subtract the area of inner circle from the area of outer circle
That is: the result is 9 π square centimeter

The height of a triangle is 7.5cm, which is half the length of its bottom. What's its area?

7.5x2x7.5÷2=56.25
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The bottom of a triangle is 5cm, the height is 7cm, and the area is 5cm______ ．

12 × 5 × 7 = 2.5 × 7 = 17.5 (cm2); answer: the area of this triangle is 17.5cm2

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