regular smooth curve - Penn Math
regular smooth curve - Penn Math
regular smooth curve - Penn Math
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Tubes about circles in the plane.<br />
The simplest example is that of a tube of radius � about a<br />
circle of radius r in the plane, so just an annulus between<br />
concentric circles of radii r + � and r � � , with area<br />
� (r + �) 2 � � (r � �) 2 = � 4r� = (2�r) (2�)<br />
= (circumference of circle) (width of tube)<br />
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