Area of an EllipseDate: 08/18/99 at 09:50:02 From: Tom Turlais Subject: Area of an ellipse I am a mentor of junior and senior high school students at a local learning center. The question has arisen: How do you calculate the area of an ellipse? Will you help with this? Date: 08/18/99 at 12:27:58 From: Doctor Peterson Subject: Re: Area of an ellipse Hi, Tom. We have a FAQ on geometrical formulas here, which may be useful: http://mathforum.org/dr.math/faq/formulas/ The area of an ellipse is very simple: A = pi a b where a and b are the semiaxes (the "radii" in each direction.) It's just the familiar "pi r squared" with each "r" replaced by one of the axes. This is because an ellipse is just a circle "stretched" in one direction, so the area is just that of the circle you start with, say with radius a, times the ratio by which you stretched it, b/a: A = pi a^2 * b/a = pi a b ***** *** | *** ** | ** * | * * | * * ...b|.... * * ... | ... * * .. | .. * *. |a .* *. | .* . | . . +-----------. . a . *. .* *. .* * .. .. * * ... ... * * ......... * * * * * ** ** *** *** ***** - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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