30.4.5 Positional Relationships Between Two Circles
30.4 The Circle: Equation and Positional Relationships
Point 5 of 6
30.4.5 Positional Relationships Between Two Circles
Core idea
As two hoops drift together, the distance d between centers against the sum and difference of the radii sorts them into five cases, from fully apart to externally tangent to overlapping.
Module goal. Write the set of points equidistant from a fixed point as an equation, master the circle's two forms, and judge tangency and intersection with lines and other circles.
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