如何计算Annulus Area
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An annulus is a ring-shaped region between two concentric circles. The annulus area calculator finds the area of this ring by subtracting the inner circle area from the outer circle area.
公式
A = π(R² − r²)
- R
- outer radius (length)
- r
- inner radius (length)
分步指南
- 1Area = π(R² − r²)
- 2Where R = outer radius and r = inner radius
- 3This is equivalent to π(R+r)(R−r)
- 4The outer radius must be greater than the inner radius
例题解析
输入
R = 10 cm, r = 6 cm
结果
Area = π(100 − 36) = 201.06 cm²
输入
R = 5, r = 3
结果
Area = π(25 − 9) = 50.27 units²
常见问题
What real-world objects are annuli?
Washers, rings, pipe cross-sections, and donuts are all examples of annuli (plural of annulus).
Can I calculate an annulus area from diameters instead of radii?
Yes, just divide each diameter by 2 to get the radius, then use the formula A = π((D₁/2)² − (D₂/2)²).
Is an annulus the same as a ring?
Yes, an annulus is the geometric term for a 2D ring shape. The 3D equivalent is a torus.
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