# Newbie: Crank and rocker issue

Hi,

I am a newbie to GeoGebra, what a fantastic software! But I realise, I have problems understanding the concepts of circles and intersects with the purpose of creating something similar to crank/rocker. I am trying to create a boat steering setup. I have attached some files.

What I want to do:

1. Vary the angle of Point(E) and then see the effect of the angle of Point(F). The distance between E and F should be constant, meaning they are connected with a rod.

I have understood that I need a number of circles with set radius, but I don't get it to work. F does not move when I move E. When I move E the segment(E,F) is just prolonged, Point(F) does not move.

I hope someone can guide me in the right direction. There are many examples of similar setups but I have not found any that explain the concept, just the finished result. I hope someone can make me undertand this a little better.

Thanks in advance!

Hi,

The attached might help. This is a geometric approach using intersecting circles, but other methods are possible. The file that ends in "...-v2.ggb" is the same approach but has the circles nested in the definitions of the points (so they aren't drawn on the Graphics view), and the points are set to trace their paths.

It's important to create E before F (and make the position of F dependent on the position of E). You can look at the construction protocol for the order used in these files.

If the attached aren't quite what you had in mind please clarify what you are looking for and I'll try to help further.

Take care,

Peter

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