# Hollow Ellipse

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.

### Area of a Hollow ellipse formula

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

### Inner Semi-major Axis Length of a Hollow ellipse formula

$$e \;=\; a - g$$
Symbol English Metric
$$a$$ = length semi-major axis $$in$$ $$mm$$
$$b$$ = length semi-minor axis $$in$$ $$mm$$
$$g$$ = ring width $$in$$ $$mm$$

### Inner Semi-minor Axis Length of a Hollow ellipse formula

$$f \;=\; b - g$$
Symbol English Metric
$$a$$ = length semi-major axis $$in$$ $$mm$$
$$b$$ = length semi-minor axis $$in$$ $$mm$$
$$g$$ = ring width $$in$$ $$mm$$

Tags: Ellipse