1. ## Turning Point

Drejepunkt.jpg

Hi.
I am trying to figure out how to find the exact turning point on something, to make it act like the picture above.

2. Originally Posted by dbergloev
Drejepunkt.jpg

Hi.
I am trying to figure out how to find the exact turning point on something, to make it act like the picture above.
By turning point - do you mean - center of rotation?

What is the topic in math class that has assigned this problem?

3. Originally Posted by dbergloev
Drejepunkt.jpg
Hi.
I am trying to figure out how to find the exact turning point on something, to make it act like the picture above.
Assuming you are looking for the center of rotation, or pivot, for the blue rectangle as it turns 90 degrees (I've seen tables designed like this), one way to find it is to think about the position of any one point (maybe a corner, or the center of the rectangle, or the center of a side) before and after the rotation. These will lie 90 degrees apart on a circle, and it is not hard to find the center of that circle if you think about it.

Once you tell us something about what you already know, and the context of the question, we may be able to give you further help if you need it.

4. Center of rotation is properly the correct phrase for it. And a table is a great example, it's actually what this is for. Have a brother who want's to build a small table where the top plate can be rotated and then be unfolded when he needs a little more space, this would fit his small studio apartment better than a regular table.

5. Originally Posted by dbergloev
Center of rotation is properly the correct phrase for it. And a table is a great example, it's actually what this is for. Have a brother who want's to build a small table where the top plate can be rotated and then be unfolded when he needs a little more space, this would fit his small studio apartment better than a regular table.
Evidently this is not for a class, so I can just point you to the answer rather than giving hints on what theorems to use.

See this page, and let me know if you need more help: Kitchen Tabletop. The author of the question later said he was inspired by an IKEA table he saw. I tried to look for clear pictures or plans for such a table, but couldn't find it.

6. Thanks a lot, this helped.
This was really bothering me because I knew that the solution was simple, I just could not quite figure it out.

7. Originally Posted by dbergloev
Thanks a lot, this helped.
This was really bothering me because I knew that the solution was simple, I just could not quite figure it out.
You're welcome! It's actually surprisingly simple to me; I initially expected it to be a little worse.

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