Perpendicular bisectors of points of circular arc dont meet at arc's center.

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Perpendicular bisectors of points of circular arc dont meet at arc's center.

chomwitt
Happy new year from Greece.

I am experimenting with the 'Method of exhaustion'' .

So i created a circular arc.
And i started to divided it by perpendicular bisector command.
I created the image below, and i noticed that the lines dont meet
at the arc's center . So i think , without giving it so far too much thought,
but intuitively i think those lines should meet at the arc's center.


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Re: Perpendicular bisectors of points of circular arc dont meet at arc's center.

chomwitt
I found it. I think..
When i create the arc with Line->Arc(Center) ,  the last of the three point can be out of the arc.



In contrast in the Line->Circle the second point is on the circle.
I think that is more practical.

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Re: Perpendicular bisectors of points of circular arc dont meet at arc's center.

Hilaire Fernandes
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Le 18/01/2021 à 09:33, chomwitt [via Dr. Geo Forum] a écrit :
I found it. I think..
When i create the arc ,  the last of the three point can be out of the arc.

Great!. That's 100% correct!

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Re: Perpendicular bisectors of points of circular arc dont meet at arc's center.

chomwitt
In that case we dont have a point for the end of the arc. Is there a way to create that point?
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Re: Perpendicular bisectors of points of circular arc dont meet at arc's center.

Hilaire Fernandes
Administrator
Hum... you can add a free point on the arc then move it at one end of
the arc.

However, I think there is a bug that when you move a free point on arc
at the end of the line, it moves back at the other extremity. I think I
never fixed this bug.

There is likely alternate way to achieve what you want to do.

Hilaire

Le 20/01/2021 à 19:04, chomwitt [via Dr. Geo Forum] a écrit :
> In that case we dont have a point for the end of the arc. Is there a
> way to create that point?
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Re: Perpendicular bisectors of points of circular arc dont meet at arc's center.

chomwitt


Ok. I've found a way.

Now i have another obstacle. How can i extend a segment to a bigger
segment or into a line ?

I tried this:
1) create a segment AB
2) create a line throught points A,B
3) create a segment giving as start point A and as the other point
    i click another point on the line of step 2.
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Re: Perpendicular bisectors of points of circular arc dont meet at arc's center.

Hilaire Fernandes
Administrator
Le 23/01/2021 à 17:01, chomwitt [via Dr. Geo Forum] a écrit :
Ok. I've found a way.

Now i have another obstacle. How can i extend a segment to a bigger
segment or into a line ?

Homothety (Scale transformation)!

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