Suppose the curve has the vector equation ,
, or, equivalently, the parametric equations
, where
are continuous.
If the curve is traversed exactly once as t increases from a to b, then it can be shown that its length is .
The curve is and the interval is
.
Consider .
Differentiate the curve with respect to .
.
Consider .
Differentiate the curve with respect to .
.
Consider .
Differentiate the curve with respect to .
.
Length of the curve over the interval
is
Let , then
.
Evaluating boundaries :
\At ,
.
At ,
.
Substitute corresponding values in .
Apply formula : .
Length of the curve over the interval
is
.