How to find crossing coordinates?

Greetings everyone,

My question is based of this .gif I’m attaching.
On this sketch, if the green part is the ground - lets say groundMC and the orange pole is poleMC (the blue dot being the center of rotation (pivot point) of poleMC).

What would a piece of code inside an poleMC.onEnterFrame function look like if it was to capture the x coordinate of the point where poleMC touches groundMC (where the red arrow is pointing at)?

You could also say that I’m trying to figure out how to tell flash the x coordinate of the exact point where the shape of poleMC enters the shape of groundMC. The collision points of all those parts of poleMC that is below the surface of groundMC doesn’t matter to me i this example - its only the “entry point” (if you can call it that) I’m looking for here…

Hope the above makes sense to you gurus…

Any suggestions to code solutions or thoughts on best approach would be very welcome.

-GB