function [l,theta_m,theta_3]= Fermeture_geometrique(theta_1)
a=0.08;
b=0.07;
c=0.08;
p=0.004;
l0=sqrt((b+c)^2+a^2);
l=sqrt((b+c*cos(theta_1))^2+(c*sin(theta_1)-a)^2);
theta_m=(l-l0)*2*pi/p;
theta_3=-acos((b+c*cos(theta_1))/l);