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If the number of radians of the center angle of a fan-shaped circle is 2 and the chord length of the sector arc is 2, then the area of the sector is () A. 1 sin21 B. 2 sin22 C. 1 cos21 D. 2 cos22
The radius of the fan is 1
sin1．
The area of the sector is: 1
2×2×1
sin21=1
sin21
So choose a
If the chord length of the central angle of a circle whose radian is 2 is 2, then the area of the sector sandwiched by the central angle of the circle is___ .
∵ if the radian is 2, the chord length corresponding to the central angle is 2,
ν radius ob = 1
sin1．
The area formula of sector s = 1
2×OB2×2=1
sin21，
So the answer is: 1
sin21．
If the arc length corresponding to the central angle of 2 radians is 4cm, then the area of the sector sandwiched by this central angle is______ .
The arc length of the center angle of a circle with radian of 2 is 4, so the radius of the circle is 2,
So the area of the sector is: 1
2×4×2=4cm2；
So the answer is 4cm2
If the arc length corresponding to the center angle of 2 radians is 2cm, what is the sector area of this central angle?
2 π: circumference of the circle = 2:2
The circumference of the circle is 2 * 2 π / 2 = 2 π,
Diameter of circle = 2cm
Radius of the circle = 1cm,
Then the area of the sector between the central angle = radius * arc length / 2 = 1 * 2 / 2 = 1 (square centimeter)
If the arc length corresponding to the central angle of the arc is 6, then the area of the sector sandwiched by the central angle of the circle is______ .
Defined by radian, α = L
r. So r = 6, so s = 1
2lr=1
2•6•6=18．
So the answer is: 18
If the arc length corresponding to the central angle of 2 radians is 4cm, then the area of the sector sandwiched by this central angle is______ .
The arc length of the center angle of a circle with radian of 2 is 4, so the radius of the circle is 2,
So the area of the sector is: 1
2×4×2=4cm2；
So the answer is 4cm2
If the arc length corresponding to the central angle of the arc is 6, then the area of the sector sandwiched by the central angle of the circle is______ .
Defined by radian, α = L
r. So r = 6, so s = 1
2lr=1
2•6•6=18．
So the answer is: 18
An 18.84 cm long wire is bent into an arc with a center angle of 120 degrees. What is the radius of the circle where the arc is located
A wire with a length of C = 18.84 cm is bent into an arc with a center angle of 120 degrees. What is the radius r of the circle where the arc is located?
A = 120 degrees = 120 * pi / 180 = 2.0944 radians
R = C / a = 18.84 / 2.0944 = 8.995cm
If the arc length to which the center angle of a circle is 120 degrees is 25.12, then the radius of the circle where the arc is located is_______ centimeter
25.12x360/120÷3.14=24
1. The length of an arc is 6.28 cm, the center angle of the circle is 270 degrees, and how many centimeters is the radius? 2. A piece of wire can be enclosed into a circle with a circumference of 12.28 cm. If the iron wire is used to form a fan with a central angle of 120 degrees, what is the radius of the fan? 3. The circumference of a circle is 40 cm. What is the arc length of 97 degree central angle of the circle? 4. There is a semicircular arch (under the bridge). The arch arc length is 62.8. Find its span? 5. A circle is made of 3.14 cm long wire. If the wire is made into a semicircle, the area of the semicircle can be calculated The above is the math problem of my son in Grade 6 of primary school. I can't do it. I have to hand it in to school tomorrow. Thank you very much!
1. Let the arc length be s, s = π R α / 180 ° [R -- the radius, α - center angle, degree] r = s * 180 / π α = 6.28 * 180 / 3.14 × 270 °
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