With two forces acting at a point, the maximum effect is obtained when their resultant is $$4$$ N. If they act at right angles, then their resultant is $$3$$ N. Then the forces are

Let the forces be $$P$$ N and $$Q$$ N.

The maximum resultant occurs when the forces act in the same direction.

Therefore,

$$P+Q=4$$

When the forces act at right angles, the resultant is

$$\sqrt{P^2+Q^2}=3$$

Hence,

$$P^2+Q^2=9$$

Now,

$$(P+Q)^2=P^2+Q^2+2PQ$$

$$16=9+2PQ$$

$$2PQ=7$$

$$PQ=\frac72$$

Therefore, $$P$$ and $$Q$$ are roots of

$$x^2-4x+\frac72=0$$

Multiplying by $$2$$,

$$2x^2-8x+7=0$$

Using the quadratic formula,

$$x=\frac{8\pm\sqrt{64-56}}{4}$$

$$=\frac{8\pm\sqrt8}{4}$$

$$=\frac{4\pm\sqrt2}{2}$$

Hence, the two forces are

$$\boxed{\frac{4+\sqrt2}{2}\text{ N and }\frac{4-\sqrt2}{2}\text{ N}}$$