1, there is no common * * * point, a circle is called external separation outside another circle, and it is called internal separation inside it.

2. If there is a common point, a circle is called circumscribed by another circle and inscribed by another circle.

There are two things in common called intersection. The distance between the centers of two circles is called the center distance.

Let the radii of two circles be r and r respectively, and r > r, and the center distance is p, then the conclusion is: the outer distance is p>R+r; Circumscribed p = r+r; Include 0

As shown in the figure:

Extended data:

The positional relationship between a straight line and a circle:

1, straight lines and circles have nothing in common, which is called separation. AB is separated from circle O, d>r.

2. A straight line and a circle have two common points, which are called intersections. This straight line is called the secant of a circle. AB intersects with o and d

A straight line and a circle have only one common point, which is called tangency. This straight line is called the tangent of the circle, and this common point is called the tangent point. The line between the center of the circle and the tangent point is perpendicular to the tangent line. AB is tangent to ⊙O, and d = r. (d is the distance from the center of the circle to the straight line)

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