Calculs préliminaires pour trouver le pas x des helices, inutiles maintenant

cof:=2*r*cos(t0/2)/sin(t0/2)*Pi/2+large*1.2:
he2:= [-r*cos(t0/2)/sin(t0/2)*t,d+r*cos(t),-r*sin(t)]:
he0:= [-r*cos(t0/2)/sin(t0/2)*t,d+r*cos(t),r*sin(t)]:
cyl0:=[u,d+(r-0.1)*cos(t),(r-0.1)*sin(t)]:
deb:=-Pi/2: fin:=Pi/2: rge_t:=deb..fin:
# --------------------------------------
hel||0:=subs(r=(n-1)*r,he0):
#hel1:=expand(rot(he2,t0)+x*dir(t0+Pi/2)+[0,0,(n-2)*r]):

a0:=simplify(subs(t=deb,hel0)): b0:=simplify(subs(t=fin,hel0)):
#c0:=simplify(subs(t=0,hel0));
#a1:=simplify(subs(t=deb,hel1)); b1:=simplify(subs(t=fin,hel1));
#c1:=simplify(subs(t=0,hel0));
#solve(norme(pv(expand(b0-a1),dir(t0/2)))^2,x);