Question 529742
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Use the slope formula


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ m\ =\ \frac{y_1\ -\ y_2}{x_1\ -\ x_2} ]


where *[tex \Large \left(x_1,y_1\right)] and *[tex \Large \left(x_2,y_2\right)] are the coordinates of the given points P and Q.


Then do it again for points R and S.


If the slope of the line through P and Q is the negative reciprocal of the slope of the line through R and S, then the lines are perpendicular.  Otherwise, not.



John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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