I have a two points, $A(x_1,y_1)$ and $B(x_2,y_2)$. They are united with a line.
Now I have a 3rd and 4th point $C(x_3,y_3)$, $D(x_4,y_4)$. The line formed by CD is going to intercept AB in point $E(x_5,y_5)$.
I know everything except $y_3, y_4$ and $y_5$, also $x_3, x_4, x_5$ are equal.
How do I find that $y_3,y_4,y_5$? Is there a formula?