On a circle with a radius of 25mm, if the length of an arc is 50mm, the radian number of the center angle of the arc is (). For detailed explanation,

On a circle with a radius of 25mm, if the length of an arc is 50mm, the radian number of the center angle of the arc is (). For detailed explanation,

The circumference of the circle is 2 π R and the corresponding degree is 360 degrees
Degrees = (50 / 2 π R) * 360 degrees = (50 / 2 * 25 * π) * 360 degrees = (50 / 50 π) * 360 degrees = (1 / π) * 360 degrees = 360 / 3.14 = 114.65 degrees

If the length of an arc with a radius of 5 is equal to the circumference of a circle with a radius of 2, the center angle of the arc is_ Degrees?

Let the center angle be θ Degrees, there are
θ/ 360*2πr1(r1=5)=2πr2(r2=2)
θ= 360*2/5
=144 degrees

If the center angle of an arc is 135 °, and the arc length is equal to 3 times the circumference of a circle with a radius of 5cm, the radius of this arc is______ cm．

Let the radius of the circle where the arc is located be r,
From the meaning of the question, 135 π R
180＝2π × five × 3，
The solution shows that r = 40cm
Therefore, it should be filled in 40

If the length of an arc with a radius of 5cm is equal to the circumference of a circle with a radius of 2cm, the center angle of the arc is_____

Let the center angle of the arc be α
∵R=5cm r=2cm
R α= 2πr
∴ α= 0.8π
(also, the answer upstairs should be 2 π R（ α/ 360 °) = 2 π R, the answer is 144 °, not 288 °)

In circle O, the length of chord AB is exactly equal to the radius. Find the size of the circumferential angle opposite arc ab Write the process clearly`

If OA is connected, OA = ob = radius, OAB is an equilateral triangle
So the angle AOB is 60 degrees
That is, the center angle of arc AB = 60 degrees
Therefore, the circumferential angle of arc AB is 30 degrees

What are the radians of the center angle of a chord with a length equal to 3 times the root of the radius? Radians of angle = L / R, the answer should not be root 3? How could it be 2 / 3 π?

L is the arc length,
Root 3 is the chord length
The chord and radius form a triangle
It should be 2 / 3 π