Circle - 2 points and radius

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Circle - 2 points and radius

jmweaver41
This post was updated on .
Hey, I'm a new user to CAD in general, so I'm not sure if I'm missing some functionality somewhere.  I typically do a lot of 2D drawing, and usually can use geometry to figure out a way to do what I want within the functionality that I know of.

Currently I'm trying to draw a circle, and the measurements I have are the radius, and I can figure out two points where it will intersect lines, although I don't think its orthagonal.

My question is, am I missing functionality to snap a circle with two points and the radius?  That should specify two possible circles, correct?  If not, is there an obvious workaround that I'm missing?

Thanks!


edit:  The best solution I've managed is to draw a circle with the correct radius through one of the points, then anchor a rotation from that point.  Going to play around and see if I can get the rotation to snap to the correct second point somehow.
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Re: Circle - 2 points and radius

dxli
one way is to use command line:

for example:

you have the two points at (30, 0) and (60,0), and you want to draw a circle passing them with a radius of 50

1, set relative zero at (30, 0)
2, Draw->Circle-> Circle, Point
3, when prompted by: "Specify Center", activate command line (clicking on it, or by spacebar)
4, type in coordinates of center:  @50<acos(15/50)*180/pi
5, when prompted by: "specify radius", type in the coordinates: 30,0

if you points are not on a horizontal line, you have to add the angle to the polar coordinates in step 4.

Doing geometry construction is fine by construction lines. However, in LibreCAD you can get the benefits of our complex math parser.

<quote author="jmweaver41">
Hey, I'm a new user to CAD in general, so I'm not sure if I'm missing some functionality somewhere.  I typically do a lot of 2D drawing, and usually can use geometry to figure out a way to do what I want within the functionality that I know of.

Currently I'm trying to draw a circle, and the measurements I have are the radius, and I can figure out two points where it will intersect lines, although I don't think its orthagonal.

My question is, am I missing functionality to snap a circle with two points and the radius?  That should specify two possible circles, correct?  If not, is there an obvious workaround that I'm missing?

Thanks!


edit:  The best solution I've managed is to draw a circle with the correct radius through one of the points, then anchor a rotation from that point.  Going to play around and see if I can get the rotation to snap to the correct second point somehow.

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Re: Circle - 2 points and radius

perepujal
In reply to this post by jmweaver41
Easiest to me:
Draw 2 helper circles the same radius as definitive, center at each intersection point
Draw the definitive circle, center at one of the 2 intersections between the 2 helper circles
Remove the helper circles
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Re: Circle - 2 points and radius

dxli
Provided by LC as a basic circle drawing method, it saves two construction circles for you. :)

perepujal wrote
Easiest to me:
Draw 2 helper circles the same radius as definitive, center at each intersection point
Draw the definitive circle, center at one of the 2 intersections between the 2 helper circles
Remove the helper circles