Theorems and corresponding algorithms are presented which produce a ra
tional Bezier curve of a specified are length subject to certain const
raints. Extraneous inflection points are avoided. The problem is reduc
ed to expressing the are length as a function of a single variable. A
general theorem from a previous paper of the authors is used which giv
es conditions under which the are length function is convex or strictl
y convex. An algorithm to automatically choose the initial parameters
for the secant method will produce a solution to this problem with per
formance comparable to the Newton-Raphson method. Theory and algorithm
s for rational parametric curves are presented. It is shown that in ce
rtain cases rational parametric curves of degree three can be used whi
le polynomials of bounded degree cannot.