Home > Construct > Line: Tangent to Two Circles

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A line that touches two circles at once.

Menu: Construct > Line: Tangent to Two Circles | In depth: Lines, rays & segments

Click one circle or arc, then a second one.

Draws a line that grazes both without crossing either. Two circles sitting apart have four such lines: the two outer ones, which keep both circles on the same side, and the two inner ones, which pass between them.

Every answer that exists for the arrangement is ghosted at once. Move the cursor to the one you want and click to keep it.

The line stays tied to both circles, so moving or resizing either one re-solves it.

If one circle sits entirely inside the other there is no common tangent, and Locus tells you rather than drawing something wrong.

< Previous: Line: Tangent to Circle | Next: Circle: Apollonius >

• Line: Tangent to Circle: the tangent from a point to a single circle.
• Circle: Apollonius: a circle touching three things at once, chosen the same way.