I have two points, $p_1$ and $p_2$, in a cartesian plane, and a fixed radius, $r$.
I want to find the coordinates of another point, $p_3$, that is in the same line of the $p_1$ and $p_2$, and always in a fixed distance, $r$, from the point $p_1$.
$(a,b)$ $(?,?)$ $\quad \quad \quad\space(c,d)$
$p_1$---------$p_3$---------------------$p_2$
$\quad r$
Considering that the points $p_1$ and $p_2$ can be on anywhere in the plane.
Thanks in advance.