Ellipses vary in shape from circular to nearly parabolic. An ellipse's eccentricity indicates the location of its foci, but its aspect ratio is a direct measure of its shape.
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Gregory D. Foley, firstname.lastname@example.org, is the Robert L. Morton Professor of Mathematics Education at Ohio University in Athens. A mathematics educator and textbook author, he advocates for inquiry-based methods and innovative uses of technology for mathematics teaching and learning at all levels, especially in grades 6-14.