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A circle at a center, sized to touch another object: a circle, arc, segment, ray or line.

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The node twin of the modeling tool of the same name. Center fixes where the circle sits and Target fixes what it has to touch; the radius is whatever makes that true. Because the node exists, Convert to Nodes can rebuild a tangent circle you drew by hand instead of reporting it unconvertible.

• Center (point): where the circle is centered.
• Target (any): the object to touch - a circle, an arc, a segment, a ray or a line.
• Far (on/off): which of the two answers to take when the target is round. Off by default.

• Geometry (region): the tangent circle.

A round target has two answers from the same center. Far off takes the near one, the circle that stops where the target begins. Far on takes the one that runs past the target, so the target is enclosed by the new circle or sits inside it.

A straight target has only one answer, the perpendicular distance to the line it lies on, and Far is ignored. A segment and a ray are read as the whole line they sit on.

The node returns nothing rather than a wrong circle when the answer does not exist: a center lying on a straight target, a center on a target circle's own center, a zero-radius target, or a zero-length one.

< Previous: Circle: Apollonius | Next: Circle: 3 Points >

• In the modeling view: Circle Tangent to... draws the same circle by clicking a center and a target.
• Circle: Apollonius - the circle touching three things at once, where the center is found rather than given.
• Circle: Center Radius - when you already know the radius.