theorem Th59: :: SIN_COS3:59

for z1, z2 being Complex holds
( ((sinh_C /. z1) * (sinh_C /. z1)) - ((sinh_C /. z2) * (sinh_C /. z2)) = (sinh_C /. (z1 + z2)) * (sinh_C /. (z1 - z2)) & ((cosh_C /. z1) * (cosh_C /. z1)) - ((cosh_C /. z2) * (cosh_C /. z2)) = (sinh_C /. (z1 + z2)) * (sinh_C /. (z1 - z2)) & ((sinh_C /. z1) * (sinh_C /. z1)) - ((sinh_C /. z2) * (sinh_C /. z2)) = ((cosh_C /. z1) * (cosh_C /. z1)) - ((cosh_C /. z2) * (cosh_C /. z2)) )