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{{ printedBook.courseTrack.name }} {{ printedBook.name }} Tangent circles are two circles that intersect only at a single point.

Tangent circles that have no common interior points are known as *externally tangent*. If one of the circles is located inside the other, they are said to be *internally tangent*.

Two or more tangent circles that are externally tangent may be the same size or different sizes. Internally tangent circles must always be of different sizes.

Two circles with radii $r_1$ and $r_2$ are externally tangent if the distance between their centers equals $r_1+r_2.$