Annulus

Written by Jerry Ratzlaff on . Posted in Plane Geometry

annulusThe area between two concentric circles.

 

Area of an Annulus formulas

\(\large{ A = \pi \;r^2 - \pi \; R^2 }\)  
\(\large{ A = \pi \; \left( r^2 - R^2 \right) }\)  

Where:

\(\large{ A }\) = area

\(\large{ \pi }\) = Pi

\(\large{ r }\) = radius (inside diamester)

\(\large{ R }\) = radius (outside diameter)

 

Area of a sector of an Annulus formula

\(\large{ A = \frac{ \pi \; \theta}{ 360^{\circ} } \; \left( R^2 - r^2 \right) }\)  

Where:

\(\large{ A }\) = area

\(\large{ \theta }\) = degree

\(\large{ \pi }\) = Pi

\(\large{ r }\) = radius (inside diamester)

\(\large{ R }\) = radius (outside diameter)

 

Breadth of an Annulus formula

\(\large{ b = R - r }\)  

Where:

\(\large{ b }\) = breadth

\(\large{ r }\) = radius (inside diamester)

\(\large{ R }\) = radius (outside diameter)

 

Longest Interval of an Annulus formula

\(\large{ l = 2 \; \sqrt{ R^2 - r^2 } }\)  

Where:

\(\large{ l }\) = longest interval

\(\large{ r }\) = radius (inside diamester)

\(\large{ R }\) = radius (outside diameter)

 

Perimeter of an Annulus formula

\(\large{ P = 2 \; \pi \; \left( R + r \right) }\)  

Where:

\(\large{ P }\) = perimeter

\(\large{ \pi }\) = Pi

\(\large{ r }\) = radius (inside diamester)

\(\large{ R }\) = radius (outside diameter)