Checking the surface area of a sphere - Geometry Made Easy
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Sphere Project

Wrapping spheres

To see how the surface area of a sphere is really 4πr2, find a ball to wrap (a basketball works well). Cut some wrapping paper to fit the ball, and then lay the wrapping paper out flat and measure it to see whether the length is about the circumference of the ball and the width is about the diameter of the ball (a little less than a third of the circumference). It won't be exactly right, because of the extra you need to be able to tape it, but it should be pretty close.

More about spheres
More about Geometry

Bibliography and further reading about circles:

More Geometry
More about Math
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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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Happy New Year! Welcome back! Get ready for Martin Luther King day with these articles about medieval Africa, slavery, the Civil War, emancipation, the civil rights movement, and Martin Luther King Jr. himself. More about King here...