Question: taylor with cos (theta1(t)-theta2(t))

Hello everybody,

I have a big expression with many cos(theta(t)) sin((theta1(t)-theta2(t))) ...
and I would like to obtain this expression linearized by taylor 1st order, so that there will be only differentials order 2.

I tried with mtaylor and taylor, but my arguments are not accepted.

A:=(1/2)*M[2]*(-2*L[1]*(diff(Theta[1](t), t, t))*e[2]*sin(Theta[1](t)-Theta[2](t))-2*L[1]*(diff(Theta[1](t), t))*e[2]*cos(Theta[1](t)-Theta[2](t))*(diff(Theta[1](t), t)-(diff(Theta[2](t), t)))+2*S[2]*(diff((sin(Theta[2]))(t), t, t))*e[2]*sin(Theta[2](t))+2*S[2]*(diff((sin(Theta[2]))(t), t))*e[2]*cos(Theta[2](t))*(diff(Theta[2](t), t))+2*e[2]^2*(diff(Theta[2](t), t, t))+2*S[2]*(diff((cos(Theta[2]))(t), t, t))*e[2]*cos(Theta[2](t))-2*S[2]*(diff((cos(Theta[2]))(t), t))*e[2]*sin(Theta[2](t))*(diff(Theta[2](t), t)));

should I use some freeze or fronted before?

Many thanks,

Ternox