Equations of Perpendicular Lines Practice

In the sketch below, drag around points A, B, and C. Write the equation of the line through C that is perpendicular to the line through A and B.
Click on the check box to check your answer or to get a hint. Repeat until you get 5 correct.

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Move the red point around, what do you notice about the slope of the perpendicular line?

Steve Phelps, Created with GeoGebra