If the radius of the big circle is twice that of the small circle, and the area of the big circle is 12 square centimeters more than that of the small circle, then the area of the small circle is () A. 12 square centimeter B. 4 square centimeter C. 6 square centimeter D. 8 square centimeter

If the radius of the big circle is twice that of the small circle, and the area of the big circle is 12 square centimeters more than that of the small circle, then the area of the small circle is () A. 12 square centimeter B. 4 square centimeter C. 6 square centimeter D. 8 square centimeter

Because the radius of the big circle is twice that of the small circle, the area of the big circle is four times that of the small circle. The area of the small circle is 12 △ (4-1) × 1 = 4 (square centimeter). Answer: the area of the small circle is 4 square centimeter, so choose B

The radius of a small circle is 12 cm. The ratio of the radius of a large circle to that of a small circle is 3:2. What is the area of a large circle in square centimeters?

It is known that the ratio of the radius of the big circle to the radius of the small circle is 3:2, and the radius of the small circle is 12 cm, then the radius of the big circle is 12 cm
12/2=6（cm） 6×3＝18（cm）
Then the area of the great circle is
π×18×18=324π≈1017.36
Answer

The radius of big circle is 5cm, and the area of small circle is 3cm

0 cangyan 0:
（5cm）²×3.14-（3cm）²×3.14
＝（25-9）cm²×3.14
＝16cm²×3.14
＝50.24cm²
A: the area of the ring is 50.24 square centimeters
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