High school mathematics radian system If 1 / 2 π is changed into angle system, some people think it's the multiplication of 1 / 2 radians of π radians, right

π = 180 degrees
Then 1 radian = 180 / π degree
1 degree = π / 180 degrees

High school mathematics -- radian system

1rad (i.e. 1 radian) = π / 180 degrees
1rad × (180 △ π) = angle
The central angle of an arc with a long radius is called the angle of 1 radian. The system of measuring the angle in radians is called the radian system
Taking the vertex of the known angle a as the center of the circle and taking any value r as the radius as the arc, then the ratio of the arc length of angle a to R is a fixed value [independent of R]. We call the positive angle when l = r an angle of 1 radian. Taking 1 radian angle as the unit of measuring angle, we call this measuring system radian system, which is different from another measuring system of angle angle system
This is the conversion between radians and degrees
Because 360 degrees = 2 * 3.14 (radians)
That is 180 degrees = 3.14 (radians)
14180 / 3.14 degrees = 1 rad (radian)
180 on both sides, 1 degree = 3.14/180 rad
For example: 3.14/6rad = (3.14 / 6) rad * (180 / 3.14) = 180 / 6 = 30 degrees
30 degrees = 30 * (3.14 / 180rad) = 3.14/6rad
Note: 3.14 is pi

On the radian system
The area of a sector is 3cm ^ 2 and its circumference is 7cm

Let the radius be r and the central angle be θ, then the area is π R ^ 2 × θ / 2 π = 3, that is, R ^ 2 × θ / 2 = 3, and the perimeter is 2 × R + θ × r = 7. Divide the two sides of the second formula by the first formula and simplify it, that is, 6 θ ^ 2-25 θ + 24 = 0, and the solution is θ = 1.5rad

Look at the picture & nbsp; the area of a square is 25 square centimeters, and the area of a circle is 25 square centimeters______ Square centimeter

Suppose the radius of the circle is r, then the diagonal of the square is 2R, then 2R × 2R △ 2 = 25, R2 = 12.5, then the area of the circle is 3.14 × 12.5 = 39.25 (square centimeter). Answer: the area of the circle is 39.25 square centimeter. So the answer is: 39.25

As shown in the figure: the area of a square is 14 square meters. How many square meters is the area of a circle?

Let the side length of a square be r meters, 3.14 × R2 = 3.14 × 14 = 43.96 square meters. A: the area of a circle is 43.96 square meters

Judgment: if the area of a circle is equal to that of a square, the circumference of the circle is greater than that of the square

Judgment:
If the area of a circle is equal to that of a square, the circumference of the circle is greater than that of the square
The circumference of the circle is less than that of the square

The side length of a square is equal to the radius of a circle
A. 78.5B. 62.8C. 12.56D. 15.7

Area of circle = π γ 2 & nbsp; & nbsp; & nbsp; area of square = γ 2 = 20 (square meter) & nbsp; & nbsp; & nbsp; area of circle = 20 π & nbsp; & nbsp; & nbsp; 20 × 3.14 = 62.8 (square meter) answer: Area of circle is 62.8 square meter

The side length of a square is equal to the radius of a circle
A. 78.5B. 62.8C. 12.56D. 15.7

If the area of a circle is equal to that of a square, what is the ratio of the circumference of a circle to that of a square?
Ask for reason, if you like,

The perimeter of the circle C = 2pi * r, the area s = pi * R ^ 2, so C0 = 2, the area of the square s = a ＾ 2, the perimeter C1 = 4A = 4, the root sign s, so C0: C1 = 2, the root sign PI: 4 = the root sign PI: 2

The radius of the big circle is equal to the diameter of the small circle. What is the perimeter ratio of the big circle to the small circle and the area ratio of the big circle to the small circle

If the radius of the big circle is equal to the diameter of the small circle, the area of the big circle is four times that of the small circle, and the ratio of the circumference of the big circle to the circumference of the small circle is 2:1

High school mathematics radian system If 1 / 2 π is changed into angle system, some people think it's the multiplication of 1 / 2 radians of π radians, right