Can anyone help me calculate the length of a 3D curve? I need to know the length from 0 degrees to 800 degrees of a curve in the form:

x(t)=(R-r)cos(t)+rcos(((R-r)/R)t)

y(t)=(R-r)sin(t)-rsin(((R-r)/R)t)

z(t)=at

I have specific values that I am using for R, r, and a. The curve is called a Hypocycloid.