theorem :: DIFF_3:53

for x0, x1 being Real holds [!((sin (#) sin) (#) sin),x0,x1!] = ((1 / 2) * (((3 * (cos ((x0 + x1) / 2))) * (sin ((x0 - x1) / 2))) - ((cos ((3 * (x0 + x1)) / 2)) * (sin ((3 * (x0 - x1)) / 2))))) / (x0 - x1)