Question

I don’t understand need help

Answer 1

Answer: Choice D

(a-e)/f

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Explanation:

Points D and B are at locations (e,f) and (a,0) respectively.

Find the slope of line DB to get

m = (y2-y1)/(x2-x1)

m = (0-f)/(a-e)

m = -f/(a-e)

This is the slope of line DB. We want the perpendicular slope to this line. So we'll flip the fraction to get -(a-e)/f and then flip the sign from negative to positive. That leads to the final answer (a-e)/f.

Another example would be an original slope of -2/5 has a perpendicular slope of 5/2. Notice how the two slopes -2/5 and 5/2 multiply to -1. This is true of any pair of perpendicular lines where neither line is vertical.