> restart; 
> with(plots):
> de:=a*diff(y(x),x,x)=sqrt(1+diff(y(x),x)^2); 
> sol1:=dsolve(de,y(x)); 
> sol2:=subs(_C1=c1,_C2=c2,remove(has,{sol1},I)[]); 
> eq1:=subs(x=0,y(0)=0,sol2); 
> Cat_Cur:=simplify(subs(c2=solve(eq1,c2),sol2)); 
> restart;
> L:=1: x2:=0.3: y2:=0.8:
> Length := L = a*(sinh((x2+c1)/a)-sinh(c1/a)):
> Cat_Cur := y2 = a*(cosh((x2+c1)/a)-cosh(c1/a)):
> fsolve({Length,Cat_Cur},{a,c1});
> fsolve({Length,Cat_Cur},{a,c1},{a=0..1});
> Order := 6:
> nullst := solve(series(sinh(z),z) = c*z, z); 
> z := convert(nullst[2],polynom); 
> f := t-> arcsinh(c*t); 
> fs := D(f); 
> K := simplify(fs(z)); 
> series(K,c=1); 




