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GeoGebraGeoGebra Classroom

Lines Tangent and Secant to a Circle的副本

The length of segment a is the distance from the center of the circle to line d. You can change the length of segment a by adjusting the slider. Use the slider and the applet to answer the questions below.
Using the slider, find the values where the line intersects the circle at a) 0 points b) 1 point c) 2 points What do you notice about the relationship between the distance the line is from the center and the number of time the line intersects the circle? For line d to be tangent to circle E, what must be true?