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IM Geo.6.8 Lesson: Equations and Graphs

The image shows a parabola with focus  and directrix  (the -axis). Points , and  are on the parabola. Without using the Pythagorean Theorem, find the distance from each plotted point to the parabola’s focus. Explain your reasoning.

The image shows a parabola with focus  and directrix  (the -axis). Write an equation that would allow you to test whether a particular point  is on the parabola.

The equation you wrote defines the parabola, but it’s not in a very easy-to-read form. Rewrite the equation to be in vertex form: , where  is the vertex.

Match each graph with the equation that represents it.

In this section, you have examined points that are equidistant from a given point and a given line. Now consider a set of points that are half as far from a point as they are from a line. Write an equation that describes the set of all points that are  as far from the point  as they are from the -axis.

Use technology to graph your equation. Sketch the graph.

Describe what it looks like.