Your question does not seem to make sense,unless what you are asking is how to convert -(5/9) radians into multiples of pi. (and then find the sine ratio of this )
I'll assume that's what you want:
there are pi radians in 180 degrees
so 1 radian = 180/pi degrees
-(5/9) radians = -(5/9) x (180/pi) degrees which represents an angle in the clockwise direction with respect to the x - axis.
...and sin( -x) = - sin(x).
