The principal curvatures are the maximum and minimum of the normal curvature 
and 
at a given point on a surface. The principal curvatures
measure the maximum and minimum
bending of a regular surface at each point. The
Gaussian curvature 
and mean curvature 
are related to 
and 
by
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(1)
|
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(2)
|
This can be written as a quadratic equation
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(3)
|
which has solutions
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(4)
|
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(5)
|
