function dxp2=droite3(xp2,x)

m=70;
mud=tan(2.5*pi/180);
T=0.2;
ro=1.19;
r1=90.3;
g=9.81;
alpha=10.5*pi/180;
dxp2=0;
dxp2=2*g*(sin(alpha)-mud*cos(alpha))-(ro*T/m)*dxp2;
