The area between two concentric circles.
Area of an Annulus formulas |
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\( A \;=\; \pi \cdot r^2 - \pi \cdot R^2 \) \( A \;=\; \pi \cdot ( r^2 - R^2 ) \) |
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| Symbol | English | Metric |
| \( A \) = area | \( in^2 \) | \( mm^2 \) |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( R \) = outside radius | \( in \) | \( mm \) |
| \( \pi \) = Pi | \(3.141 592 653 ...\) | \(3.141 592 653 ...\) |
Inside Radius of an Annulus formula |
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| \( r \;=\; \sqrt{ R^2 - \dfrac{ A }{ \pi } } \) | ||
| Symbol | English | Metric |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( A \) = area | \( in^2 \) | \( mm^2 \) |
| \( R \) = outside radius | \( in \) | \( mm \) |
| \( \pi \) = Pi | \(3.141 592 653 ...\) | \(3.141 592 653 ...\) |
Outside Radius of an Annulus formula |
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| \( R \;=\; \sqrt{ r^2 - \dfrac{ A }{ \pi } } \) | ||
| Symbol | English | Metric |
| \( R \) = outside radius | \( in \) | \( mm \) |
| \( A \) = area | \( in^2 \) | \( mm^2 \) |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( \pi \) = Pi | \(3.141 592 653 ...\) | \(3.141 592 653 ...\) |
Area of a sector of an Annulus formula |
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| \( A \;=\; \dfrac{ \pi \cdot \theta }{ 360^{\circ} } \cdot ( R^2 - r^2 ) \) | ||
| Symbol | English | Metric |
| \( A \) = area | \( in^2 \) | \( mm^2 \) |
| \( \theta \) = degree | \( deg \) | \( rad \) |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( R \) = outside radius | \( in \) | \( mm \) |
| \( \pi \) = Pi | \(3.141 592 653 ...\) | \(3.141 592 653 ...\) |
Breadth of an Annulus formula |
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| \( b \;=\; R - r \) | ||
| Symbol | English | Metric |
| \( b \) = breadth | \( in \) | \( mm \) |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( R \) = outside radius | \( in \) | \( mm \) |
Longest Interval of an Annulus formula |
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| \( l \;=\; 2 \cdot \sqrt{ R^2 - r^2 } \) | ||
| Symbol | English | Metric |
| \( l \) = longest interval | \( in \) | \( mm \) |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( R \) = outside radius | \( in \) | \( mm \) |
Perimeter of an Annulus formula |
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| \( P \;=\; 2 \cdot \pi \cdot ( R + r ) \) | ||
| Symbol | English | Metric |
| \( P \) = perimeter | \( in \) | \( mm \) |
| \( r \) = inside radius | \( in \) | \( mm \) |
| \( R \) = outside radius | \( in \) | \( mm \) |
| \( \pi \) = Pi | \(3.141 592 653 ...\) | \(3.141 592 653 ...\) |
