1, the positional relationship between a point and a circle

If the radius of the circle is r and the distance from the point to the center of the circle is d, the positional relationship can be expressed by a quantitative relationship.

The point (1) d > r is outside the circle;

(2) point D = R is on the circle;

(3) point D < r is in the circle.

2. The positional relationship between a straight line and a circle

Three positional relationships: intersection, tangency and separation.

3. The positional relationship between circles.

Separation, circumscribed, intersected, inscribed and contained.

Determined by the center distance and the length of two radii,

The center distance is represented by d, and the radii of the two circles are represented by r and r respectively.

When d & gtR+r

When? Leave each other.

When d=R+r

Time, limit

When R-r

Q:

I asked you to do this problem. Why did you give me these?

Answer:

Option d

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