Cases of Tangent Circles

Below, two original circles are highlighted in black. The common tangent circle and the locus of its center are highlighted in red. The locus of the midpoint of the base of the isosceles triangle formed in the construction is displayed in light blue. Click on each link to see an animation of the locus. Pictures of the intersecting and disjoint circle cases can be obtained through the links.

Smaller circle contained in a larger one.
    Smaller circle is external to common tangent circle.


Smaller circle is internal to common tangent circle.


Intersecting circles.
    Click on the animation buttons to see two different common tangents.


Disjoint circles.

One of the common tangent circles.


The other common tangent circle.

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