IM 8.2.12 Lesson: Using Equations for Lines

A dilation with scale factor 2 sends A to B. Where is the center of the dilation?
Here is a line.
Using what you know about similar triangles, find an equation for the line in the diagram. (You can use the applet above to help).
[size=150][size=100]What is the slope of this line? Does it appear in your equation?[/size][/size]
Is [math](9,11)[/math] also on the line?
How do you know?
Is [math](100,193)[/math] also on the line?
There are many different ways to write down an equation for a line like the one in the problem.
Does [math]\frac{y-3}{x-6}=2[/math] represent the line? Explain your reasoning.
What about [math]\frac{y-6}{x-4}=5[/math]? Explain your reasoning.
What about [math]\frac{y+5}{x-1}=2[/math]?  Explain your reasoning.
Here is triangle ABC. Draw the dilation of triangle ABC with center (0,1) and scale factor 2.
Here is triangle ABC. Draw the dilation of triangle ABC with center (0,1) and scale factor 2.5.
Where is C mapped by the dilation with center (0, 1) and scale factor s?
For which scale factor does the dilation with center (0, 1) send C to (9, 5.5)?
Explain how you know.
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– GeoGebra Classroom Activities, IM 6 – 8 Math

Information: IM 8.2.12 Lesson: Using Equations for Lines