New User - How do you create negative angle of rotation on the unit circle?

J F Ahearn shared this question 2 years ago

I am a new Geometry/Trigonometry teacher and also a new user to the Geogebra App and am trying to learn how to create a negative angle of rotation on a unit circle. Although there are many wonderful pre-existing models available for download and use, I would like to learn how to create the Geogebra model myfself. Unfortunately, I have spent the past 1.5 hours combing through the existing Questions in the topic bank and have not been able to find a reply which adequately addresses my situation. Nor have I been able to find a video on YouTube. Moreover, inspecting the Construction Protocols of several of the pre-existing models left me a bit overwhelmed by the various methods for obtaining the desired outcome.

My goal is to learn how to program Geogebra well enough to create solutions for my students - which are attending class virtually during the Covid Pandemic. The attached file contains an example of what I am trying to accomplish on page 3. I can create triangles on the unit circle using positive angles of rotation but do not know how to create a negative angle of rotation.

If anyone could direct me to a good resource which would allow me to obtain my goal, then I would be much obliged for a reply to this post.


JF Ahearn

Comments (2)


Please post your .ggb file so we can see how far you've got

Probably you need to put a point in the position you want for the negative angle eg

P = (cos(-α), sin(-α))
then you can draw the angle in the position you want like

Angle(P,(0,0), (1,0))


Thank you for the quick reply and willingness to help. The attached file is very simple and I did not create any Trig functions.

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