This is the conclusion of a three day lesson applying right triangles. Here is day 1 and day 2. Eric is my apprentice teacher and he initiated this discussion:
Eric: Yesterday we prepared to go outside, what information did we collect?
student: How much rope we need and what angle.
Eric: Where is the angle? Here or here? What else did we find?
student: The height of the flagpole.
student: The distance away from the flagpole
Eric: One person from each group come up to the board and write your angle and distance from the flagpole on the board.
Eric: Let’s make a plan before we go outside.
We then discussed and agreed that we should actually measure the height of the flagpole when we put barbie on the pole. We also decided to find the exact ground distance to create a 30 degree angle, but that it looks like it should be approximately 45 feet from the base of the flagpole. Students also agreed that they would like to confirm their thinking that this angle will result in a safe speed for Barbie to zipline down from the top of the flagpole.
The Wrap Up
Eric made a sheet for students to reflect on the lesson.
Crazy Math Teacher Lady 
Thank you for sharing and including the videos and resources! I plan on trying very soon and your post was so helpful in getting the process planned!