function ret = angle(Fp,Fw,U,V,a,L,mu,rho,Cdt,Cds,guess)



global FP;
global FW;
global UU;
global VV;
global A;
global LL;
global MU;
global RHO;
global CDT;
global CDS;

FP = Fp;
FW = Fw;
UU = U;
VV = V;
A = a;
LL = L;
MU = mu;
RHO = rho;
CDT = Cdt;
CDS = Cds;
if (guess > 0) 
 ret = fzero(@f,guess);
else
 ret = -10.0;
end





function ret = f(theta)
global FP;
global FW;
global UU;
global VV;
global A;
global LL;
global MU;
global RHO;
global CDT;
global CDS;
ret = FP - MU*(CDS*RHO*A*LL*realpow(UU*cos(theta),2.0)+FW*sin(theta)) +FW*cos(theta)-CDT*pi*RHO*A*A*realpow(UU*sin(theta)+VV,2.0);