The distance from the point $ (x_0, y_0) $ to the line $ Ax + By + C = 0 $ is given by:

$$ d = \frac{ \left| Ax_0 + B_yo + C \right| }{ \sqrt{A^2 + B^2}} $$

To apply this formula, we first need to express the line in standard form

$$\begin{aligned} y & = -3 \\y+3&=0\end{aligned}$$

After substituting: $ A = 0 $ , $ B = 1 $ , $ C = 3 $ , $ x_0 = 4 $ and $ y_0 = 3 $ we have:

$$ \begin{aligned} d =& \frac{ \left| 0\cdot4 +1\cdot3 + 3 \right| }{\sqrt{ 0^2 + 1^2}} = \\ d =& \frac{ \left| 0 + 3 + 3 \right| }{\sqrt{ 0 + 1}} = \\ d =& \frac{ \left| 6 \right| }{\sqrt{ 1}} = \\ d =& \frac{ 6 }{ 1 } = \\ d =& 6 \end{aligned} $$

Line-point distance calculator