A vector has magnitude same as that of $$\vec{A} = 3\hat{i} + 4\hat{j}$$ and is parallel to $$\vec{B} = 4\hat{i} + 3\hat{j}$$. The $$x$$ and $$y$$ components of this vector in first quadrant are $$x$$ and 3 respectively where $$x$$ = ____.

$$|\vec{A}| = \sqrt{9 + 16} = 5$$. $$\vec{B} = 4\hat{i} + 3\hat{j}$$, $$|\vec{B}| = 5$$.

Unit vector along $$\vec{B}$$: $$\hat{B} = \frac{4\hat{i} + 3\hat{j}}{5}$$.

Required vector = $$5\hat{B} = 4\hat{i} + 3\hat{j}$$.

The x-component is 4 and y-component is 3.

Therefore, $$x = \boxed{4}$$.