Why is the arc formula L = n π R / 180? I can't understand why n should be multiplied by π R. isn't 2 π R △ 360 ° multiplied by the number of radians to get the arc length?

Why is the arc formula L = n π R / 180? I can't understand why n should be multiplied by π R. isn't 2 π R △ 360 ° multiplied by the number of radians to get the arc length?

N is the degree

The circumference of a circle is 6.28cm, and its area is
Thank you for your trouble

Radius = 6.28 △ 3.14 △ 2 = 1cm
Area = 1 × 1 × 3.14 = 3.14 square centimeter

The circumference of a semicircle is 10.28cm, which is used to form the largest cone, and the bottom area of the cone is calculated

Let the radius of the semicircle be r, then 2R + 3.14r = 10.28, and R = 2
The length of semicircle arc is 6.28
The base circumference of the largest cone is equal to the arc length of the semicircle
If the bottom radius is r, then 6.28r = 6.28 and R = 1
So the bottom area is 3.14

The perimeter of a circle is equal to that of a square. Given that the side length of a square is 6.28cm, what is the area of a circle

The radius of the circle is 6.28 * 4 / 3.14 / 2 = 4cm, and the area is 4 * 4 * 3.14 = 50.24cm2

The area of rectangle and circle is equal, the width of rectangle is equal to the radius of circle, and the circumference of circle is 20c
The distance between the circle and the rectangle is 8cm. Now the circle and the rectangle move to the right at the same time, the circle is 5cm per second, and the rectangle is 3cm per second. When moving for four seconds, find the perimeter of the non overlapping part. Well said, add a reward!

Because the distance between the circle and the rectangle is 8cm, the circle and the rectangle are just tangent. If there is no overlap, the result is the circumference of the rectangle plus the circumference of the circle * width = π R ^ 2, width = R2 π r = 20, so r = 10 / π rectangle circumference = 2 (length +...)

It is known that the area of a rectangle is equal to that of a circle. The length of the rectangle is 6.28cm, and the width is the radius of the circle?

The area of the circle is the square of the radius * 3.14, while the area of the rectangle is 6.28 * radius, and the area of the rectangle is equal to the area of the circle, so the square of the radius * 3.14 = 6.28 * radius, so the radius is 2 cm
So the circumference of the circle is 3.14 * 2 * 2 = 12.56 cm

The area of a circle is equal to that of a rectangle. If the length of a rectangle is 5cm, what is the circumference of a circle?

Because the distance from the center of a 5cm square to each side is 2.5, the maximum circle radius is 2.5cm
So the perimeter is π d = 2.5 * π (approximately equal to 3.14) = 8.85

The area difference between the two circles is 57 square centimeters. The perimeter of circle a is 11 / 8 times that of circle B. what is the area of circle B?

Let R be the radius of circle a and R be the radius of circle B,
πR²-πr²=57
2Rπ=11*2*r π/8
We can get R & # 178; = 64 / π
The area of circle B is π R & # 178; = 64

If the circumference of a circle is doubled, how many times is its area?

4 times

If the circumference of a circle is expanded four times, how many times is its area expanded?

Perimeter = 2 * radius * pi
Area = square of radius * pi
If the perimeter is increased by four times, the radius must be increased by four times. Naturally, the area is increased by 16 times