Find the slope of the line that is (a) parallel and (b) perpendicular to the line through the pair of points. (−2,−7) and (8,4)

Hey there! 

First, find the slope of the actual original pair of points.
The slope formula is:



So now, substitute the points in, whichever order you substitute the points into the equation doesn't matter, as long as the ones substituted in with the same subscript number.

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Once you subtract, you get:



So the slope is 11/10.

A line that is parallel to another has the exact same slope that that another line has.

So therefore the line that is parallel has a slope of 11/10.

Perpendicular is another story. You take the reciprocal of the slope of the other line, and then change the sign before it: ex: negative would become positive.

So therefore the line that is perpendicular has a slope of -10/11.