| Examples: The circle for is a simple closed curve. The oriented boundary of a regular polygon is a simple closed curve. Whereas, any curve of shape of the number is a closed curve, but not a simple curve. The straight line segment for where is a simple curve, but not a closed curve. The curve for is a simple curve, but not a closed curve. Jordan Curve Theorem: The points on any simple close curve (Jordan curve) are boundary points of two distinct domains, one of which is the interior of and is bounded. The other, which is the exterior of is unbounded. Definition (Differentiable Curve): A curve ( ) is said to be a differentiable curve if the derivative exist and continuous for . Examples: The circle for , the straight line segment for and the curve for are differentiable curves. Note: If ( ) is a differentiable curve then the length of the curve from and is given by 
Suppose has a different parametric representation. Then also the value of the length of curve is invariant. |