Two forces one of 10N and another of 6N, act upon a body. The directions of the forces are unknown. The resultant force on the body is

If the two forces are in the same direction, the magnitude of the resultant force will be $10+6=16N.$ On the other hand if the forces are in opposite directions the resultant force will be $10-6=4N.$For all other angles between the forces, the resultant will be between 4N and 16 N.