function F = fbnd_secondary(x,c)
%% terms::
%-----------------------------------
y=sqrt(x(4));y_1=y/sqrt(cos(x(3)));
l_2=(0.5-x(5))/2; % length
%% define system of equations:
%----------------------------------------------------------------
F(1)=(x(1)-x(3))*sin(y_1*x(5))/sqrt(cos(x(3)))-x(2)*sin(y*l_2);
fun_1=@(s) sin((x(1)-x(3))*cos(y*s)+x(3));
F(2) = integral(fun_1,0,x(5))-c(2);
fun_2=@(s) sin(x(2)*cos(y*s));
F(3) = integral(fun_2,0,l_2)-c(1)/2;
F(4)=y_1-acos(-x(3)/(x(1)-x(3)))/x(5);
F(5)=y-0.5*pi/l_2;
end