solving equation in the time

hello,   I have a program where I try to solve this system:

cos(theta)=cos(b)*[sin(f)*sin(d)+cos(d)*cos(f)*cos(w)]+sin(b)*[cos(d)*sin(g)*cos(w)*sin(f)-cos(g)*sin(d)*cos(f)+cos(d)*sin(w)*sin(g)] and

cos (theta) = cos (b) * sin (h) -cos (A) [sin (b) * cos (h) * cos (l)] - sin (a) * [sin (l) sin (b) * cos (h)]

such as: h, f, w, d, g, l are precalculated parameters changing during time; I try to extract every time ti,'a' and 'b' such that 0.98<cos (theta)<=1, I try with "solve" function but it gives that I haven't a digital result .... i try it also with lsqnonlin, but non result... have you proposed solution?