Two circles that cannot have a common tangent:

" In Euclidean plane geometry, a tangent line to a circle is a line that touches the circle at exactly one point, never entering the circle's interior ".

Common tangent: A common tangent is a line that is tangent to two circles. If the tangent crosses the line segment joining the centers of the two circles, it is said to be an internal common tangent; otherwise, it is an external common tangent.

Now we can see what the common tangents are and also some of the example such that there are no common tangents with the help of the diagram attached to the answer.

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