Formulas of Arc Length

Some important results and formulas regarding the Arc Length of the curve is listed here:

1.  Arc length for Cartesian curve y = f\left( x \right) is given by

S = \int\limits_{{x_1}}^{{x_2}}  {\sqrt {1 + {{\left( {\frac{{dy}}{{dx}}} \right)}^2}} } dx

2.  If the parametric form x = f\left( t \right) and y = g\left( t \right)is given, then

S = \int\limits_\alpha ^\beta {\sqrt {{{\left( {\frac{{dy}}{{dt}}}  \right)}^2} + {{\left( {\frac{{dv}}{{dt}}} \right)}^2}} }  dt\,\,\,{\text{where}}\,\,\,\alpha  \leqslant t \leqslant \beta

3.  The arc length if the equation of a curve in polar system i.e., r = f\left( \theta  \right) is given by

S =  \int\limits_{{\theta _1}}^{{\theta _2}} {\sqrt {{r^2} + {{\left(  {\frac{{dr}}{{d\theta }}} \right)}^2}} } d\theta

4.  If the equation of the curve is given by\theta = f\left( r \right), then arc length is given by

S = \int\limits_{{r_1}}^{{r_2}}  {\sqrt {1 + {{\left( {r\frac{{d\theta }}{{dr}}} \right)}^2}} } dr



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