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If the circumference of a sector with radius 2 is equal to the arc length of its semicircle, then the central angle of the sector is___ Radian, the sector area is___ .
Arc length formula: l = n π R / 180
nπR/180＋2R=πR
nπ/180＋2=π
N = (π - 2) × (π / 180) ≈ 65 degrees
Area: S = (65 × 3.14 × 4) / 360 (4 is the square of radius 2)
≈2.27
If the circumference of a sector with radius 1 is equal to the arc length of the semicircle of its circle, what radian is the central angle of the sector? What is the area of the sector?
Radius r = 1, arc length L, perimeter = L + R + r = L + 2;
Arc length of semicircle = 2 π * 1 / 2 = π;
L+2=π,L=π-2;
The radius is 1, so the center angle of the sector = π - 2 (radian), [or, the center angle of the sector: 2 π = (π - 2): 2 π * 1]
The area of sector = L * r / 2 = (π - 2) * 1 / 2 = π / 2-1
Given that the length of an arc is equal to the circumference of the inscribed square of its circle, then the absolute value of the radian number of its central angle is urgent!
Square perimeter: 4 √ 2 * r
And the arc length is 4 √ 2 * r
Just change the number of radians with the formula (I forgot)
The center angle of the fan is 15O degrees, and its radius is 3cm. Its area is? The arc length of the fan is 12.56cm, the radius is 5cm, and its area is?
1.π×150×3²／360=15π／4㎝²
2.½×12.56×5=31.4㎝²
Given that the center angle of the sector is 120 degrees and the arc length is 6 π cm, what is the area of the sector
If the center angle of the circle is 120, the sector is a third circle
So the arc length L = 1 / 3 * 2 π r = 6 π, r = 9
So the sector area s = 1 / 3 * π * 9 square = 27 π
If the length of an arc is 12 π cm and the angle of the center of the circle to which the arc is opposite is 36 degrees, then the circumference of the circle whose radius is equal to its length is () cm (the result retains π)
120 π method: 12 π x 360 △ 36
An arc AB on a circle is 86 cm. If the center angle of the arc is 720 °, what is the circumference of the circle
720 divided by 360 = 2
A. The two arcs of B are equal in length. The center angle of a arc is half of that of B arc. The circumference of a circle is compared with that of B arc () A. The circumference of B. a arc is larger than that of B. B. the circumference of C. B arc is longer than D. It is uncertain
If the arc length is l and the center angle of a arc is α, then the center angle of arc B is 2 α,
So the radius of a arc is L / α, and that of B arc is L / (2 α),
The ratio of circumference is equal to the ratio of radius, which is 2 to 1
So choose B
Divide a circle into three sectors, and calculate the area ratio of the three sectors with the angle ratio of 2:3:4
A circle is divided into three sectors, the angle ratio of the center is 2:3:4, and the area ratio of the three sectors is 2:3:4
If the ratio of the area of each sector is 4:3:2:1, then the degrees of their respective central angles are______ 、______ 、______ 、______ .
∵ the ratio of each sector area is 4:3:2:1,
The area of each sector accounts for 2% of the total circle area
5，3
10，1
5，1
10，
The degree of the center angle of each sector is 360 °× 2
5＝144°，360°×3
10＝108°，360°×1
5＝72°，360°×1
10＝36°．
Therefore, it is necessary to fill in 144, 108, 72 and 36 degrees
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