Length of arc?

[Anonymous]

Can't remember how to do this in trig, been way too many years.
And can't seem to figure out how to get AC to measure the length
of this arc. either with spline or polyline.

I'm sure I missing the obvious but have run out of ideas.
I've tried holding down ctr/alt keys etc,etc to get it to add all together but each point I click resets length to zero again.
And bending straight line so far gives no joy.
help would be great.

[Anonymous]

Select the arc then go to
Window->Pallets->Element Information
and click on the second icon from the left.
Peter Devlin

[Anonymous]

I found on the web an equation for arc length
that does not involve trig or calculus.

C is the central angle
R is the radius
∏ is Ludolph's constant
(3.1415926....)
Peter Devlin

[Anonymous]

The dimensioning tool has an arc-length geometry style for measuring arcs.

[David Maudlin]

Peter wrote:
Select the arc then go to Window->Pallets->Element Information and click on the second icon from the left.

Be sure to draw the arc counter-clockwise, or the angle and length will be wrong. Looks like a bug.

David

[Anonymous]

Hello David,
I could not reproduce the clockwise counterclockwise bug
in either AC 10 or AC 12.
Could it be that what works correctly in AC 10 or AC 12 got busted in AC 14 ?
If you still have an AC version earlier than AC 14, see if it works correctly in that version.
Thanks,
Peter Devlin

[Anonymous]

Thanks all for the replies.

David, I tried both directions with the spline tool (14) and Element Info gave me the same length.

zpf, Could not get dimension tool to measure arc, my ignorance there I suppose.

Peter, thanks for the formula, took me a minute, but I got it.

Thanks again everyone.

[Anonymous]

Select the tool, then select the arc geometry method like in the attached pic, click on the edge of the arc you want to dimension, click twice outside (or inside) of the arc to generate the dimension, click once more to place it. That should be it.

[Anonymous]

Duh, I was trying to make it work on a spline "arc".
Thanks zpr

[Laszlo Nagy]

David wrote:

Peter wrote:
Select the arc then go to Window->Pallets->Element Information and click on the second icon from the left.

Be sure to draw the arc counter-clockwise, or the angle and length will be wrong. Looks like a bug.

David

I get this bug too.
I also get it if I draw counterclockwise, then mirror it. The angle of the mirrored arc will be incorrectly reported.
So I send this to GS.