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I am trying to draw an arc from one circle to another with a specific radius. I know that in Auto CAD you can draw an arc with tan, tan, radius. I was wondering if anybody knew the QCAD equivalent?

- 3D-P
- Registered Member
**Posts:**1**Joined:**Tue Jul 29, 2008 6:26 pm

Here's how I've done it. It's a bit of head-standing but I believe it gets it done. Probably be best if I give an example:

Say you have two circles of radii 6 and 10 that you want to connect with an arc of radius 40. If you construct circles of radius 34 (40-6) and 30 (40-10) respectively centered on the 6 and 10 sized circles the new circles intersect at the center of your desired arc.

I also added construction lines from the center of the arc through the centers of the circles and extended them with trim (rm) to the circles circumference as that defines the tangent point for starting the arc (or breaking the circle into arcs). This extra stuff gets deleted once the arcs are made. Hope this helps!

Say you have two circles of radii 6 and 10 that you want to connect with an arc of radius 40. If you construct circles of radius 34 (40-6) and 30 (40-10) respectively centered on the 6 and 10 sized circles the new circles intersect at the center of your desired arc.

I also added construction lines from the center of the arc through the centers of the circles and extended them with trim (rm) to the circles circumference as that defines the tangent point for starting the arc (or breaking the circle into arcs). This extra stuff gets deleted once the arcs are made. Hope this helps!

- prollymolly
- Newbie Member
**Posts:**4**Joined:**Tue Sep 16, 2008 10:24 pm

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