1. Measure the distance between each focus point (a, b) and a single, shared point on the perimeter of the ellipse. 2. Add the two distances together: (a + b) This is the diameter
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Formulas for a circle: Radius: r Diameter: d Circumference: C Area: A d = 2r C = 2 Pi r = Pi d A = Pi r² = Pi d²/4 C = 2 sqrt(Pi A) A = C²/4 Pi = Cr/2 http://mathforum.org
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