# Hollow Ellipse

Written by Jerry Ratzlaff on . Posted in Plane Geometry

• Hollow ellipse (a two-dimensional figure) has two ellipses with a conic section or a stretched circle.
• The major axis is always the longest axis in an ellipse.
• The minor axis is always the shortest axis in an ellipse.

## Hollow ellipse Area formula

 $$\large{ A_{area} = \pi \; \left( a \; b - e \; f \right) }$$

### Where:

 Units English Metric $$\large{ A }$$ = area $$\large{ in^2 }$$ $$\large{ mm^2 }$$ $$\large{ a }$$ = length semi-major axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ b }$$ = length semi-minor axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ e }$$ = length inner semi-major axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ f }$$ = length inner semi-minor axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ \pi }$$ = Pi $$\large{3.141 592 653 ...}$$

## Hollow ellipse Inner Semi-major Axis Length formula

 $$\large{ e = a-g }$$

### Where:

 Units English Metric $$\large{ a }$$ = length semi-major axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ b }$$ = length semi-minor axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ g }$$ = ring width $$\large{ in }$$ $$\large{ mm }$$

## Hollow ellipse Inner Semi-minor Axis Length formula

 $$\large{ f = b-g }$$

### Where:

 Units English Metric $$\large{ a }$$ = length semi-major axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ b }$$ = length semi-minor axis $$\large{ in }$$ $$\large{ mm }$$ $$\large{ g }$$ = ring width $$\large{ in }$$ $$\large{ mm }$$