The perimeter ratio of the two circles is 4:5, and the area ratio of the two circles is 4:5______ ．

The perimeter ratio of the two circles is 4:5, and the area ratio of the two circles is 4:5______ ．

Let two circles be r and R respectively, so the radius ratio: 2 π R: 2 π r = 4:5, so r: r = 4:5; the area ratio: π R2: π R2 = 42:52 = 16:25; so the area ratio is 16:25; so the answer is: 16:25

The area of the circle in the picture is 21.98 square centimeter, so how many square centimeter is the area of the square?

r. R = 21.98 △ 3.14 = 7 2x7 = 14 (square centimeter)
The largest square in the circle has an area of 14 square centimeters

The circumference of a circle is reduced by 1 / 3. Now the area of the circle is 91 square decimeters less than before. What's the area of the circle now

If the perimeter is reduced by 1 / 3, then the ratio between the perimeter and the original perimeter is 2:3 and the ratio between the perimeter and the original area is 4:9. Therefore, the area of the circle is 91 divided by 5 and multiplied by 4

There are eight sectors in a sector statistical chart. The size of six sectors accounts for two-thirds of the area of the circle, and the sum of the areas of the other two sectors accounts for the area of the circle
How much is it?

It's 1-2 / 3 = 1 / 3

There are 20 science and technology books, 30 story books and 10 fairy tales books in the library corner of grade 5 (1). If the fan-shaped statistical chart is made, what are the degrees of the three fan-shaped circles

20 + 30 + 10 = 60
20/60=1/3
30/60=1/2
10/60=1/6
360°*1/3=120°
360°*1/2=180°
360°*1/6=60°

In a sector statistical chart, if the center angle of a part is 36 degrees, the percentage of the part in the total is______ %．

36°÷360°×100%=10%．

How to calculate the degree of the center angle of a sector statistical graph

The relationship between the degree and percentage of the center angle of the sector is: degree of the center angle = percentage * 360 degrees
method
1. Calculate the percentage of each area in unit one
2. Use 360 (degree of circle) to multiply the fraction to find the degree of the angle to be drawn

In a sector statistical chart, if the central angle of one sector is 135 degrees, then the percentage of this sector in the total is
A% 50 B% 30 C% 25 d% 37.5

D
135°/360°=0.375=37.5％

Given that the radius of the sector is 2 cm and the area is 4 / 3 π square cm, what is the central angle of the sector

Let the central angle of the sector be x degrees
π×2²×X／360=4／3π
X／360=1／3
X=120
A: the central angle of the sector is 120 degrees

In the unit circle, what is the area of the sector opposite by the angle with the center angle of 144 degrees

s'/s=144/360=0.4
That is, the sector area is 0.4 times of the circle area
Unit circle is a circle with radius 1 and center at the origin of coordinate
therefore
S sector = π · R · R × 0.4 = π × 1 × 1 × 0.4
S sector = 0.4 π
S sector = 1.256