how to make x(t) a real function in matlab symbolics?

Hi,

I have a rotation matrix (R) in which I used elements such as sin(x(t)),

to do this I have defined x and t as syms t real x=sym('x(t)')

From this definition, MATLAB knows that t is a real number but does not understand that x is also a real number. because when I calculate transpose of the rotation matrix (R') it gives me

sin(conj(x(t)))

how to make MATLAB understand that all of my functions are real valued functions?

Thanks Ehsan