If the circumference of a circle is 69.124mm. Find the area of the circle ,correct to 1 decimal place. (Take 3.142)?
回答 (6)
2017-08-20 1:17 pm
✔ 最佳答案
C: circumferenceR: radius
A: area
C = 2 × π × R
R = C / (2 × π)
R = 69.124 / (2 × 3.142) mm
R = 11 mm
A = π × R²
A = 3.142 × 11² mm
Area, A = 380.2 mm²
2017-08-20 4:00 pm
A = 𝛑 r ²
C = 𝛑 2r = 69.124mm
r = 11.001426286284173mm ((don't round until the very end))
A = 𝛑 r ² = 380.231295306553594mm²
rounded A = 380.2mm²
C = 𝛑 2r = 69.124mm
r = 11.001426286284173mm ((don't round until the very end))
A = 𝛑 r ² = 380.231295306553594mm²
rounded A = 380.2mm²
2017-08-20 2:19 pm
r = 69.124/6.284 = 11
Area = 3.142*121
= 380.2mm
Area = 3.142*121
= 380.2mm
2017-08-20 4:14 pm
C = 2 π r
r = C / 2π
r = 69•124 / 2π = 11 mm
A = 121 π mm²
A = 380•1 mm²
r = C / 2π
r = 69•124 / 2π = 11 mm
A = 121 π mm²
A = 380•1 mm²
2017-08-20 3:00 pm
A = C^2/(4π) ≈ (69.124 mm)^2/(4*3.142) ≈ 380.2 mm^2
2017-08-20 1:57 pm
The area of a circle is given by the formula A = π r^2, where A is the area and r is the radius. The circumference of a circle is C = 2 π r.
If we "solve for r" in the second equation, we have r = C / (2 π ). Now we use this to replace r in the first equation: A = π [ C / (2 π ) ]^2.
When we simplify this, we get
A
= C^2 / (4 π)
= (69.124)^2 / (4 × 3.1416)
= 380.2304... mm^2
Now you can put your value of C into this equation and find A.
Remember, π is about 3.1416.
If we "solve for r" in the second equation, we have r = C / (2 π ). Now we use this to replace r in the first equation: A = π [ C / (2 π ) ]^2.
When we simplify this, we get
A
= C^2 / (4 π)
= (69.124)^2 / (4 × 3.1416)
= 380.2304... mm^2
Now you can put your value of C into this equation and find A.
Remember, π is about 3.1416.
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