They are the common tangents to the circles.
it intersects the segment joining the centers of two circles
Common external tangents and common internal tangents are two types of tangents that can be drawn between two circles. Common external tangents touch each circle at one point without intersecting the line segment joining the circles' centers, while common internal tangents intersect this line segment. The key difference lies in their geometric relationship to the circles: external tangents do not pass between the circles, whereas internal tangents do. Each type can be determined based on the relative positions and sizes of the circles involved.
no
skew
perpendicular bisector
it intersects the segment joining the centers of two circles
intersecting lines
no
skew
an intersecting line segment is when two line segments cross together
perpendicular bisector
A bisector.
It's when two lines cross eachother
A triangle is not a segment joining a vertex and the midpoint of the side opposite the vertex.
chord
the radius
A line segment joining two adjacent vertices of a polygon is called an edge or a side. A line segment joining two non-adjacent vertices is called a diagonal.