Foci of an Ellipse

Written by Jerry Ratzlaff on . Posted in Plane Geometry

Foci of an Ellipseellipse 3c

Foci is a point used to define the conic section.  \(F\) and \(G\) seperately are called "focus", both togeather are called "foci".

Foci of an Ellipse formula

\(c^2 = a^2 - b^2  \)          \( center \; to \; focus^2  \;=\;  semi-major \; axis^2  \;-\;  semi-minor \; axis^2  \)        


\(c\) = length center to focus

\(a\) = length semi-major axis

\(b\) = length semi-minor axis

\(F\) and \(G\) = focus