30.4.4 Line and Circle: Apart, Tangent, or Crossing
30.4 The Circle: Equation and Positional Relationships
Point 4 of 6
30.4.4 Line and Circle: Apart, Tangent, or Crossing
Core idea
Compare the distance d from the center to the line against the radius r, and which is bigger decides whether they touch or cut through.
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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