If the surface area of a cone is known to be ACM ^ 2 and its side view is a sector with a center angle of 90 °, then the diameter of the bottom of the cone is

If the surface area of a cone is known to be ACM ^ 2 and its side view is a sector with a center angle of 90 °, then the diameter of the bottom of the cone is

Suppose that the bottom radius of the cone is r, according to the meaning of the topic, its ground perimeter 2 π R is equal to one fourth of the circumference of the circle with the generatrix as the radius, so we can get the generatrix length L = 4R, so its surface area is: π R ^ 2 + π RL = π R ^ 2 + π r 4R = 5 π R ^ 2 = a, we can solve R

The perimeter ratio of the big and small circles is 6:5, the area of the big circle is 72 square decimeters, and the area of the small circle is how many square decimeters? (formula calculation)

Radius ratio = 6:5;
Area ratio = 6 & # 178;: 5 & # 178; = 36:25;
Small circle area = 25 × 72 △ 36 = 50 square decimeters;
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The circumference of the outer circle is 28.56 cm, and the area of the outer circle is () square cm?

Is it 28.26 cm?
Radius of outer circle = 28.26 △ 3.14 △ 2 = 4.5 (CM)
The area of the outer circle = 3.14 × 4.5 × 4.5 = 63.585 (square centimeter)

The circumference of one circle is 12.56 cm, and the area of the other circle is 12.5 square cm. The two circles are equal in size
The closer the positive and negative numbers are to 0, the smaller their values are
The circumference of one circle is 12.56 cm, and the area of the other circle is 12.56 square cm. The two circles are equal in size
dial the wrong number

1. Wrong. Different radius, different size
2. Wrong. The closer a negative number is to zero, the greater its value

The circumference of a circle is 12.56 cm, and the area of the circle is ()

The radius is: 12.56 △ 3.14 △ 2 = 2 (CM)
Area: 3.14 × 2 × 2 = 12.56 (square centimeter)

The circumference of a circle is 8.56 cm longer than its diameter. What is the area of a circle,

Let the diameter of the circle be x cm and the circumference be 3.14 x cm
3·14x－x=8·56
2·14x=8·56
x=4
4 △ 2 = 2 (CM) 3.14 × 2 & # 178; = 12.56 (cm 2)
A: the area of a circle is 12.56 square centimeters

After converting a circle into a rectangle, the circumference of the rectangle is 6 cm more than that of the circle. The original area of the circle is

Simple
It can be solved by equation

After a circle is transformed into a rectangle, the circumference of the rectangle is increased by 20cm compared with that of the circle. The original area of the circle is ()

If the title means to divide a circle into several small arcs, and then put them together into a rectangle, then the extra 20cm is twice the radius of the circle. The original radius of the circle is r = 10cm, and the area is s = π 10 & # 178; = 100 π CM & # 178;

After a circle is transformed into a rectangle, the circumference of the rectangle is 6 cm more than that of the circle. What is the area of the original circle?

6 / 2 = 3cm, which is the radius of the original circle
The original area of the circle is: 3 * 3 * 3.14 = 28.26 square centimeters

When a circle is enlarged, its area is 8 times more than the original, and its perimeter is 50.24 times more than the original?
Dear friends, I'm still a student in Grade 6. Try to be simple and easy to understand. You can use the equation, but it can't be too difficult. Please help me solve the problem for you who will be rich in 2015

8+1=9
9=3x3
The original girth is 50.24 (3-1) = 25.12
Radius 25.12 △ 2x3.14 = 4
Area 4x4x3.14 = 50.24
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