PSAT Math : How to find the slope of perpendicular lines

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #61 : Psat Mathematics

Axes_1

Give the slope of a line perpendicular to the line in the above figure.

Possible Answers:

None of the other responses is correct.

Correct answer:

Explanation:

In order to move from the upper left point to the lower right point, it is necessary to move down 3 units and right six units. This is a rise of  and a run of 6. The slope of a line is the ratio of rise to run, so slope of the line shown is .

A line perpendicular to this will have a slope equal to the opposite of the reciprocal of . This is .

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