The radius of the small circle is 2.5cm, the diameter of the large circle is 15cm, the ratio of the circumference of the small circle to that of the large circle is () and the ratio of the area of the large circle to that of the small circle is ()

The radius of the small circle is 2.5cm, the diameter of the large circle is 15cm, the ratio of the circumference of the small circle to that of the large circle is () and the ratio of the area of the large circle to that of the small circle is ()

The ratio of small circumference to large circumference is (1 / 3)
（2.5×2）：15
=5 ：15
=1/3
The ratio of large circle area to small circle area is (9:1)
15² ：（2.5×2）²
=9 ：1

The radii of the two circles are 3cm and 5cm respectively, and the ratio of their diameters is______ What's the ratio of circumference______ What's the area ratio______ ．

From the meaning of the question, we can find out the diameter and ratio of two circles: 2 × 3:2 × 5 = 3:5; find out the perimeter and ratio of two circles: 2 π × 3:2 π × 5 = 3:5; find out the area and ratio of two circles: π × 32: π × 52 = 9:25; so the answer is: 3:5, 3:5, 9:25

The diameter of the small circle is 3 / 4 of that of the big circle. The circumference of the big circle is 25.12cm. What is the area of the small circle?
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Big circle diameter = 25.12 / (3.14) = 8 cm
Small circle diameter = 8 × 3 / 4 = 6cm
Radius of small circle = 6 / 2 = 3cm
Small circle area = 3.14 × 3 × 3 = 28.26 square centimeter

The diameter of the small circle is half of that of the big circle. The circumference of the big circle is 25.12cm. How many square meters is the area of the small circle?

Big circle radius r = 25.12 / (2 π) = 4 cm
Large circle area s = π R ^ 2 = π * 4 ^ 2 = 50.265 cm ^ 2
Small circle area s = s * (1 / 2) ^ 2 = 50.265 * (1 / 2) ^ 2 = 12.57 cm ^ 2

The radius of the small circle is 1 / 3 of that of the big circle, the circumference of the big circle is 12cm, and the radius of the small circle is 1 / 3 of that of the big circle?

The radius of the small circle is one third of that of the big circle, the circumference of the big circle is 12cm, and the circumference of the small circle is 12 * 1 / 3 = 4cm

The diameter of the big circle is 6cm, the radius of the small circle is 2cm, and the area ratio of the small circle to the big circle is ()

6÷2=3CM
3×3×3.14=28.26cm²
2×2×3.14=12.56cm²
12.56:28.26=4:9
The diameter of the big circle is 6cm, the radius of the small circle is 2cm, and the area ratio of the small circle to the big circle is (4:9)

The sum of the circumference of the two circles is 94.2cm. It is known that the radius of the big circle is four times that of the small circle. What is the radius of the small circle? What is the area of the small circle?% d% a

The radius of small circle is 94.2 △ 3.14 △ 4 + 1 = 94.2 △ 6.28 △ 5 = 3cm, and the area is 3x3x3.14 = 28.26cm2

The perimeter difference of the two circles is 94.2cm. The radius of the big circle is twice the diameter of the small circle
Want a formula

2 π R-2 π r = 94.2; r = 2 × 2R
S = S1 + S2 = π × R × R + π × R × r = 3.142 (12 × 12 + 3 × 3) = 480.726 square centimeter
The area sum of the two circles is 480.726 square centimeters

The perimeter difference of two circles is 94.2cm. The radius of the big circle is twice the diameter of the small circle. The sum of the areas of the two circles is calculated
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If the diameter of the small circle is x, then the radius of the large circle is 2x
3.14x+3.14×2×2x=94.2;
15.7x=94.2;
x=6;
So the area of small circle = 3.14 × (6 △ 2) & # 178; = 28.26cm & # 178;;
Large circle area = 3.14 × 12 & # 178; = 452.16cm & # 178;;
Area sum = 480.42cm & # 178;;

The sum of the circumference of the two circles is 94.2 meters. It is known that the radius of the big circle is four times that of the small circle. The area of the two circles can be calculated

The radius of the big circle is four times that of the small one
Circumference of big circle = 4 circumference of small circle
Radius of small circle = 94.2 △ 3.14 △ 2 (1 + 4) = 3cm
Big circle radius = 3 × 4 = 12 cm
Small circle area = 3 × 3 × 3.14 = 28.26 square centimeter
Large circle area = 12 × 12 × 3.14 = 452.16 square centimeter