Question

If two forces Fsub1 and Fsub2 each of magnitude 10N act on an object from perpendicular directions, then the effect is the same as that of a single force of 10N acting in a direction 45 degrees to each of the forces Fsub1 and Fsub2.

The answer is false.

Could you explain to me why the answer is false? If possible , could you please show me the working step? Thank you very much.